Hewlett-Packard still reigns supreme in the PC market, but Apple has hurdled into the third spot, tied with Dell and just behind Acer, according to a report released today.

According to market researcher Canalys, the worldwide PC industry grew 19 percent year over year in the fourth quarter with a total of 105.8 million devices shipped.

The growth is impressive, but it should be noted that the figures Canalys released include tablets. The company calls the category "pads" in its report.

"Pads gave the market momentum in 2010, just as Netbooks did the year before," Canalys senior analyst Daryl Chiam said in a statement. "We are encouraging vendors to plan for the future and not to remain stuck in the past."

That momentum is apparent in Apple's year-over-year growth. The company shipped 11.5 million Macs and iPads worldwide in the fourth quarter, allowing it to capture 10.8 percent of the global PC market. A year earlier, Apple shipped 3.4 million Macs, garnering the company just 3.8 percent share. Apple's year-over-year growth last quarter was 241 percent.

Even with the iPad's help, Apple couldn't supplant HP as the world's top PC maker in the fourth quarter. HP company shipped 18.7 million PC units during the period and owned 17.7 percent of the worldwide market. It was followed by Acer's 13.6 million unit sales and 12.8 percent market share. Acer saw its year-over-year shipments grow 8.8 percent in the fourth quarter, while HP saw 2.9 percent growth, Canalys said.

Dell's shipments grew year over year by 10.6 percent, but the company's market share declined from 11.6 percent in 2009 to 10.8 percent in 2010. It shipped 11.4 million units during the fourth quarter.

Canalys' decision to include tablet shipments in its research may irk some who believe they have no place in the company's data on desktops, Netbooks, notebooks, and server PCs. But the research firm believes that tablets legitimately belong there.

"Any argument that a pad is not a PC is simply out of sync," Chiam said. "With screen sizes of 7 inches or above, ample processing power, and a growing number of applications, pads offer a computing experience comparable to Netbooks. They compete for the same customers and will happily coexist."