2 Individual and Distinct Windows Session from 1 Computer. Possible? How impractical?

Hey Logan and Wendall and Quaid. Wanna start out by saying you guys are awesome and definitely were a great help to me building my first computer recently and increasing my interest in what is possible with technology. Hypothetical question. Now would it be possible to run to 2 entirely separate sessions of Windows XP, Vista, 7, 8, or 8.1 from one computer? Would it be possible to run one to one monitor and the other to another monitor and have a mouse and keyboard for each one individually? Essentially be able to have 1 computer, act as 2 computers? And have the sessions able to run intensive programs.

And on the side, if this is possible, what kind of hardware would it take? I'm just curious don't actually plan on doing it and am aware that it is most likely highly impractical. I'm only interested in whether it is possible and what hardware would be required to do that.

Thanks for reading this, Keep putting out awesome content

You can run a virtual box on a single pc and be running two different os's, but aside from compatibility issues (which is why 7 had xp mode) not really sure why you would want to do it.  But yeah something like you mentioned is possible on practically every semi modern pc.