Windows 8 will include a PDF reader, greater customization of the Aero interface, and a new version of Internet Explorer 9 that works like its Windows Phone counterpart, according to new details posted online by Microsoft partners.

Offering new tidbits and screenshots from a Windows 8 pre-beta build, "Windows 8 Secrets" co-authors Rafael Rivera and Paul Thurrott revealed some notable new features this week via the Web site Within Windows.

Windows 8 will reportedly offer a new interface dubbed Immersive as an alternative to the traditional Aero user interface introduced in Vista, according to Windows 8 Center and other sources. The new interface will borrow much of the look and feel from the tiled Metro user interface found in Windows Phone.

As one example unlocked so far, Rivera and Thurrott showed screenshots from a new "Immersive" edition of Internet Explorer 9 that renders pages like the current desktop version but looks and feels like the mobile browser found in Windows Phone.

Windows 8 also will come with its own PDF reader, according to the latest details. Known as Modern Reader, the new application will let people view PDFs in their natural format, zoom in and out, and navigate from page to page.

Modern Reader will also be based on a new type of application package called AppX, which Rivera and Thurrott believe will give developers the ability to more easily design and deploy programs for both computers and mobile devices. As one example, AppX would help developers write applications for both Windows 8 and Windows Phone 8. Windows 8 Center also points to AppX as an important step toward a Windows App Store that Microsoft is reportedly planning.

Another tidbit on Windows 8 shows a tweak to the Aero interface. In Windows 7, the color of the Aero interface stays the same no matter what background is displayed. But a new option in Windows 8 changes the Aero window color to better match and blend in with the desktop wallpaper behind it.

You find the screenshots by clicking on the links below:

One more Windows 8 feature reportedly in the works, according to WinRumors, is History Vault. Similar to Apple's Time Machine, the History Vault would automatically back up files on the fly and let people restore them from a specific date and time.

The latest news about Windows 8 follows earlier revelations that the OS would sport a new welcome screen and expand the use of the Ribbon interface.