Do you have to wait at least 15 seconds before rebooting your computer Experts weigh in on that myth and others.

For as long as I can remember, whenever I've needed to reboot my computer, I've always shut it down, counted off 15 seconds, and then started it back up.

Why Because at some point in the distant past, someone somewhere told me that to avoid damaging them, computers need a minimum of 15 seconds of downtime whenever they're rebooted.

Whether or not that was true, I've followed the advice ever since, and I can't tell you how many times I've powered down, counted off "one-one thousand, two-one thousand, three-one thousand..." for 15 seconds and then powered back up.

Not long ago, I started thinking about that habit. Why did I do that Even if it had once been a necessity, was it still Or was that 15-second "rule" nothing more than a myth. And that, in turn, got me thinking about what other great myths about technology are floating around our geared-up world

So, in no particular order, what follows is an anthology of sorts of some of the best myths about tech that my friends, my Twitter followers, my co-workers, and I could come up with.

You must wait 15 seconds before rebooting your computer Since this is the myth that got me started on this, it's the first one I'll address.

I decided that since this was a hardware question, the best place to turn was to the Geek Squad, those hearty IT folks in the black and white VW Beetles. Last week, I spoke with Ismael Matos, a Geek Squad deputy field marshal, and asked him about the 15 seconds myth, as well as several others having to do with hardware.

Matos said that the question of how long to wait before rebooting a computer has to do with the health of the plates of the hard drive. Since the plates are spinning at speeds of up to 10,000 rpm, and need to come to a stop before rebooting, "it's definitely good that you wait just a little while" before restarting the machine.

But 15 seconds That might be overkill, Matos suggested, though it certainly couldn't hurt.

"I'd say 5 seconds is [OK]," Matos said, "but 15 seconds to be on the safe side. If you want peace of mind, then 15 seconds is OK, but it's not a rule that's set in stone."

Size matters (in megapixels) If you've listened to any camera marketing, you've probably had it pounded into your head that with megapixels, more is better. And of course, the more megapixels you want, the more you have to spend. What a coincidence.

Do megapixels matter

But the reality may not back the camera companies' marketing.

As photographer and self-described photography expert Ken Rockwell puts it, "sharpness depends more on your photographic skill than the number of megapixels, because most people's sloppy technique or subject motion blurs the image more than the width of a microscopic pixel.

"Even when megapixels mattered, there was little visible difference between cameras with seemingly different ratings. For instance, a 3-megapixel [photo] pretty much looks the same as a 6-megapixel [photo], even when blown up to" 12 inches by 18 inches.

The Geek Squad's Matos would seem to agree. While he says that megapixels might matter if you're trying to put together a mural--or its cousin, a billboard--the average camera user would almost never see the difference between photos taken with most lower-megapixel and higher-megapixel cameras.

"You really start noticing the differences when you blow the picture up," Matos said. But "it really depends on the size of the image, and how much you plan on blowing it up...If you blow it up to 16 by 20 [inches], you'll still maintain the quality, and you won't notice any difference in quality" with fewer megapixels.

You have to run your battery all the way down before you charge it This is one I've heard for a long time, especially when you're talking about what to do when you first get a new battery-operated gadget.

And while it's not that hard to imagine running the juice on a new device all the way down before charging it the very first time, that's not at all an easy thing to do on an ongoing basis given that we often find ourselves fearing being away from a power source and, therefore, charging up as a precautionary measure.

But Matos said that the best possible thing you can do for your device's battery is, in fact, to run it down to zero before re-charging, each and every time.

"If you start plugging an AC adapter in while it's half-charged," Matos said, "components in the battery start to settle, and so it doesn't maintain its ability to re-charge, and so you end up weakening the battery a lot quicker."

Matos said that, ideally, we'd all run our batteries down all the way every time, but he acknowledged that's not realistic for most people. So he nods to reality: "It's recommended, so whenever possible...just let the battery drain completely before you charge it up."

No need to cry over spilled coffee on your keyboard.

You can put a keyboard you've spilled coffee on in the dishwasher Though this might be a myth that would get you to shake your head in pity at anyone who believes it--let alone practices it--Matos said that, in fact, it's true.

It only applies to wired keyboards, though' Nothing with a battery, or wireless components in it will keep operating after being run through your dishwasher.

But Matos said that as long as you don't use soap or warm or hot water, a cycle through the Kenmore will wash away the coffee and get you pounding away at the QWERTY before you know it.

Anything stored digitally will last longer than that on analog media It's a lovely idea that once you've put something on your hard drive, or some other form of digital backup, you can depend on it being there in perpetuity. It certainly seems like it should be true. After all, digital seems impervious to the passage of time, right

But counting on ever-lasting storage of your crucial 1s and 0s may well be a fool's game. According to the Associated Press, many important digital recordings are "at risk of being lost much faster than older ones on tape, and many are already gone."

The problem, the study cited by the AP reported, is that digital files run the risk of being corrupted, and some physical forms of digital media, such as CD-R discs, can begin breaking down in as little as three years.

And the same seems to be true of online recordings. "I think we're assuming that if it's on the Web, it's going to be there forever," Sam Brylawski, the co-author of a Library of Congress study on sound, told the AP. "That's one of the biggest challenges.

One part of the dilemma surrounding digital storage of audio and other important records, is that we've become trained to use such media given its ubiquity and its ease of use. "But the problem," Brylawski told the AP, "is they must be constantly maintained and backed up by audio experts as technology changes. That requires active preservation, rather than simply placing files on a shelf."

Turning a computer on and off regularly is bad for it Another myth I heard when I canvassed my social networks was that a computer can be damaged over time by being regularly turned on and off.

In fact, said the Geek Squad's Matos, it's specifically recommended that you do power your machine off on a daily basis, for example at the end of each work day.

According to Matos, "Every computer needs its rest time," in part to be sure that if you're away from it and there are power fluctuations or surges, it isn't damaged by them.

As well, he said, it's recommended that if you're going to be away from your computer for small periods of time, you let it go to sleep while you're gone. But in any case, he said, a regular on/off pattern is definitely good for the computer, not bad.

Macs are immune to viruses This myth is one that is pushed relentlessly, both overtly and subtly, by Mac fans, and, of course, by Apple. Everyone knows that Windows machines are constantly being bombarded by malware and that keeping them secure is a never-ending task.

But you rarely hear about such things from Mac users, and the common theory is that it's because Apple's computers are simply safe from being attacked.

Not so fast. It does seem, as has been well-reported, that that are far fewer exploits hitting Macs than their Windows-based cousins. But it's hardly because Macs are immune from attack. Indeed, according to security researcher Nitesh Dhanjani, it has much more to do with market share--there simply aren't anywhere near as many Macs out there as there are Windows machines.

"If we were to flip the market share, we would see a lot more exploitation in the wild," Dhanjani told my CNET colleague Elinor Mills earlier this year. "More specifically, browser security is one of the more important items to consider today from a risk perspective. I know Internet Explorer has had a considerable share of vulnerabilities, but the Safari Web browser also has a lousy reputation in the security community--it almost seems a child's play to locate an exploitable condition in Safari. Apple really needs to get its act together with Safari since OS X is enjoying a healthy market share climb at the moment."

Other security experts seem to agree that Macs' relative lack of virus problems has much more to do with the computer's market share than any kind of actual fortitude against attack. As Halvar Flake, head of research and CEO of Zynamics, told Mills, "Vista/Win7 has more extensive countermeasures against attacks and a codebase with presumably fewer security issues. But it's the operating system of the majority of users, hence making it profitable to attack. Attackers will therefore spend lots of time bypassing the countermeasures. Mac OS has fewer countermeasures and lots of easily exploitable bugs, but the market share is low, making it a less likely target."

Then again, the market share dynamic does, in fact, mean that Macs are less likely to get hit, so in that sense, they are safer. "For an everyday consumer that just wants to use a computer and not worry about getting owned with every click of the mouse, I'd go for a Mac," Joe Grand, president of Grand Idea Studio, told Mills.

Is your ISP tracking everything

Your ISP is tracking everything you do This may not be something most people are thinking about, but for those constantly worried about digital privacy, it is a signature concern, since, if true, everyone would be subject to tracking because we almost all have to get online through an Internet service provider.

Your ISP "is your local link to the worldwide computer network known as the Internet," Dave Roos wrote on Get Stuff. Every page request you make and every e-mail you send must travel through your ISP's routers first. It would seem, therefore, that your ISP has the power to scan and save every piece of data that flows through its system."

But before you get alarmed, Roos also wrote: "The truth is that it does have the power. Fortunately for us, it doesn't have the money or the desire to archive every bit of information that comes its way. ISPs in the United States don't routinely save the Web surfing histories and e-mail conversations of their users. It would simply be too expensive to save all of that data and the public outcry from privacy rights and civil liberties organizations would be deafening."

Girls don't play video games The stereotype of gamers is clearly a teenage boy sitting in front of his Xbox, pounding away at one Halo or Call of Duty game or another for hours and hours on end. And while the industry certainly brings in many, many, many millions of dollars because of that pimply-faced teen, he's by no means the only face of the gaming community.

Indeed, women and girls make up a very large bloc of gamers--they just are a little more quiet about it.

"Girls and young women are a 'pot of gold' for the [video game] industry," George VanHorn, a senior analyst at market research firm IBISWorld, told Reuters. "The gaming industry has market characteristics that many would die for."

Reuters reported that in an IBISWorld study, "38 percent of U.S. gamers are female, up from 33 percent in just five years. From January through August of 2008, females ages 18 to 45 made up 28 percent of the total industry revenue, ranking second to males ages 18 to 45, who made up 37 percent."

So while they may not be the largest group of gamers, it's clear that women and girls are spending their fair share of time playing.

Anything you delete from your hard drive is gone forever Given that we lay our lives bare on our computers--what with doing personal banking, storing family photos, researching our medical conditions, and so forth--it would be comforting to be able to believe that if we erase something on our computers, we don't have to worry about that data being available to anyone who might want to access it later.

Sadly, that would be a naive assumption. The truth is, it's very difficult to permanently get rid of your data. And if you want to do so, you probably need to go get a drill.

That's the advice of the Geek Squad's Matos, who said that, "When you delete [data], yes, [its] icon may be gone, but that information is still intact on the hard drive. The only thing the computer does is [mark] that section to be overwritten. It just gives the operating system the OK to write over that area."

So if the operating system isn't actually removing the data from your hard drive, how can you get rid of it

Matos said it's not so easy, and you may not ever want to just hand an old computer off to someone else if you're worried about them accessing your private data.

The only way to ensure that no one can ever access it is to bring tools to bear. "Let's say you're getting rid of an old computer," Matos said. "You're going to want to take the old hard drive, take a drill, and drill 10 to 12 holes through the drive--and not in a straight line. Scatter the holes and make sure they go straight through."