OK, here's what I have and what I'd like to do.... I bought a (new) Dell 8400 off eBay. It came with a 40GB HD and a 3.4 GHz CPU. I used the 3.4 CPU in another computer and purchased a 3.8 GHz for this computer. I also used the ram in the other computer. Needless to say this computer has never been used as it's been without memory. I just ordered more ram and a WD Raptor HD. What am I going to have to do to install the OS (Windows XP with SP2) on the new HD so I can get this computer up and running?