There is new feature in sight for Windows 7. It is called Windows XP Mode and it will allow you to run Windows XP applications in virtualized environment.
Nice thing about this will be that XP windows will just open without showing the whole XP desktop. This is quite significant since whenever virtualization is employed, some reeducation needs to be done. Now education will consist of simple: "Just click shortcut and window will appear." line. For "standard" consumer, everything should look the same (ok, title bar is giveaway).
P.S. If this feature seems like something you saw somewhere, there is more-or-less same feature in VirtualBox. It is called seamless mode there.