Check out this link if you havent already.
http://windows.microsoft.com/en-us/windows7/install-and-use-windows-xp-mode-in-windows-7
Under the "Before You Begin" paragraph you can download a tool that will check all of your hardware to see if you are capable of virtualization.
Make sure you're running Windows 7 Professional, Enterprise, or Ultimate.
To use Windows XP Mode, you need to download and install
Windows XP Mode AND Windows Virtual PC.
Here you can download both:
http://www.microsoft.com/windows/virtual-pc/