Re: Windows 7
Vista will be upgraded during an install, but I think you can just have it install in the same folder and have it rename the old. I know with XP, it renames it Windows.old. This is perfect, just delete that when you're done, same as a clean install, pretty much.
I think I'm going to burn one of my many XP keys on my install, I see no point in installing XP anymore, at least on this machine.