Windows 7 only: We already showed you how to set up and use XP Mode in Windows 7 using the beta version of XP Mode; now XP Mode has updated from beta to a new release candidate for your XP virtualisation needs.
Just point your browser at the Windows XP Mode and Virtual PC download page, follow the installation instructions, and you're ready to go with the latest and greatest. Once you've done that, hit up our guide to using XP Mode for more specifics on getting it up and running with specific apps on your Windows 7 machine.
If you've been using XP Mode regularly on your Win7 PC, let's hear how it's been working for you in the comments.
Windows XP Mode and Windows Virtual PC [Microsoft]