I'm thinking about replacing my cpu&motherboard if I keep the same hard drives will I have to reinstall windows? I have a compaq that came with windows installed and I dont have the discs to reinstall it.
Normally whether it works or not is a moot point. I've had xp work fine for me after swapping out a motherboard, but for stability purposes when you're talking about changing out hardware as significant as your motherboard you always want to reinstall.
You don't actually have to reinstall XP if you change the hardware.
Just use the repair option from the windows CD, and it'll wipe/reinstall the drivers, and pick up your new hardware.
You will, of course, have to deal with reactivating XP after this though