Well, you can use your own Windows Install Disc to install Windows on the base version of VPC, but later versions of Windows require activation, so that only one installation is allowed.
So, depending on your Windows version (I believe it began with XP) there is a small hurdle to overcome before it can be used on more than one PC. Earlier versions have licensing issues that may limit the number of computers you may install Windows, but nothing actually stopping you.
All of these issues can be resolved with a carefully crafted Google search. I, however, can not express them here.