What you can do is save your virtual system to a file on an internal or external storage device, and then move it to another physical computer that also has virtualization software. You can then run your virtual PC on the other machine and have your desktop, programs, files, etc. on "your" machine. Instead of your PC being a physical box, monitor, keyboard, etc., it's a file that you can run on any physical box (as long as that box has the same virtualization software).
I realize as I write this that it's not easy to explain, but it's really cool. Here's the Wikipedia entry for virtualization; it goes into more technical detail but may be even harder to understand.
I'm not sure what all it does.. i have only used it a couple times... And... well... others here are probably more "experts at it"