I am buying a recertified desktop........Pentium 945........for my wife that comes with Win XP pro. I could keep that system for all she will do with it, but have a Win 7 upgrade for 3 computers. The computer with XP only has a 80gb hard drive so I want to increase that to something larger. How can I upgrade the hard drive and keep the Win XP on the new drive so I might be able to upgrade the new drive to Win 7? I'm sure the recertified Computer does not come with a Win XP disc. Is it possible to keep the 80 gig hard drive as a boot drive and add a larger drive as a slave onto which I could load the upgrade for Win 7?