Windows 7 supports hardware virtualization. Basically what that means is you will be able to run multiple virtual computers each having exclusive control of your pc hardware on your host computer. If you’d like to learn more about virtualization, there is some great info over at Wikipedia. Unfortunately not all processors support hardware virtualization, but there is a way to check and see if yours does.
A program called Securable will check and see if your processor can handle virtualization. It is my understanding that all 64bit processors can do it, but don’t hold me to that.