Alright so I'm building myself a computer with new parts, and I'm getting a free Win 7 OS late December, but I'm getting my computer built before then. So to keep my OS(XP), do I re-use my hard drive in the new computer until I get my new OS? My Hard Drive is a model drive, so I don't know any information about the hard drive, I don't whether if it's IDE or SATA, as my computer is almost 8 years old. So I just need to know how to keep my current OS, I think I just re-use the hard drive, but I'm not exactly sure.
If you're changing your motherboard, you'll very likely want to reinstall the OS. It is possible to do a special repair of windows to bypass the major problems of using a different motherboard, but in my experience it's never perfect.
I generally do reinstall the OS on any system that is going to be used for something that needs perfect running. This machine I'm posting on is literally just used for browsing, listening to music and watching videos (audio slaved via optical to my other PC and outputs to speakers), and has been through about ten different motherboards without a reinstall of XP. Easier to wipe device manager and run a repair than reinstall everything