XP Mode doesn't work on consumer Windows 7 editions.
It needs a CPU with hardware VT support.
It's not consumer-friendly - mostly for techies.
Worst of all, you still have to reinstall all your apps, configure everything, etc..

What I use is Zinstall XP7. It does everything XP Mode does, runs on any Windows, any CPU and it automatically moves all your XP apps into the VM - no reinstalls!

Check it out at http://www.zinstall.com