A little clarification, as long as you have a legal activated copy up and
running on the computer, yes I do believe you can install to a different
Drive or partition. Before you install though, there are programs out
there that you can run to retrieve your install key. But for the life of me
I can't think of the name right now.
I'm sure someone here will supply it. Edit.
I remember now http://www.magicaljellybean.com/
This should do the trick.