A clever new feature in Windows 7 is the Windows XP Compatibility Mode, that will make it easier for companies and individual users to upgrade from Windows XP to Windows 7 because all of their existing applications will work. This will ensure that Windows 7 will be fully compatible with both Windows Vista and Windows XP.
The article has 16 screenshots of the new Windows XP Compatibility Mode in action, curteousy of Paul Thurrott.
Here is the link to the entire article and the pictures.
http://windows7news.com/2009/04/25/screenshots-of-windows-7s-new-windows-xp-mode-feature/