EDIT: Problem has been resolved with me just buying a new HD and a Windows 7 system builder's kit since the HD I wanted to use might be/is broken. There are solutions in this thread if you are having a similar problem.
Ok so I bought a Dell a few years ago with Vista and we will call this OLD. I upgraded it several times including to Windows 7 student upgrade recently. OLD no longer meets my needs so I am making a new computer from the upgrades I put in the Dell and several pieces I bought. Basically I am taking the ODD and HDD from the Dell I own and the rest is new parts to make a computer we will call NEW.
Now my Dad got a Dell with XP in like 03 or 04 and its about to break, call it DAD I guess. So I am giving him my computer that will be the stock Dell computer aka OLD minus the ODD and HDD. I will take his ODD and HDD from DAD and put it in OLD.
These are both OEM from Dell but the upgrade to Windows 7 lets me put the OS on any system I want right?
Will NEW accept the HDD from OLD?
So should I upgrade DAD to windows 7 and then xfer it to OLD?
Should I transfer DAD to OLD and then upgrade to Windows 7?
DAD: P4 about to die, BSOD
OLD : XPS 410 upgraded, currently 2.13Ghz C2D, 4GB DDR2 667hz Ram (added 2GB), 9800 GTX+ 1GB, 700W OCZ PS, default mobo, Windows 7 Student
(I have all parts safe and ready to put back in to stock settings)
Taking parts from DAD: ODDs + HDD, Win XP (upgrade to Windows 7)
New parts: Coolermaster Case, i5 760 Lynnfield 2.8Ghz, 4GB DDR3, Gigabit Mobo
Taking from old: 9800 GTX+ 1GB, 700W PS, Windows 7 Student, HDD, ODD
DAD doesn't matter, OLD and NEW need to run. NEW Needs OLD's HDD because it has all my info and Office 2010 which I need for college.