Microsoft's Windows 7

After much anticipation, Microsoft's latest operating system is finally here.

Windows 7 is now available in new PCs and on retailers' shelves. The follow-up to 2006's Windows Vista promises increased performance, streaming media functionality, a new taskbar, Device Stage, HomeGroup networking, XP Mode, and touch capabilities.

The OS is available in three editions: Home Premium, Professional, and Ultimate. Users can purchase the full software or an upgrade version for XP or Vista machines.

A Windows 7 Home Premium upgrade will cost $119.99 and the full package will retail for $199.99. The Windows 7 Professional upgrade will cost $199.99 and the full system will be $299.99. For Windows 7 Ultimate, the upgrade version will retail for $219.99 and the full version will set you back $319.99.

Customers who bought a PC with Vista Home Premium or higher on June 26 or later are eligible for a free upgrade to Windows 7. To test whether your PC and software are compatible with Windows 7, Microsoft has released an Upgrade Advisor and Compatibility Center.

Microsoft has had some bumps along the way, including a run-in with European Union antitrust officials, who are now testing a "ballot browser" that would require Microsoft to provide options other than Internet Explorer during Windows 7 installation.