This is an older tutorial, but it helped me save a lot of time. I've been using it for quite a while now. I had an older pre-SP2 XP install CD. Every time I reformatted and reinstalled (roughly once every 3 months), I would have to install XP, then install SP2, which as anyone who has had to install it before knows, takes quite a while.
Using this method, you slipstream SP2 into the XP install files, then burn the new copy and install from the copy. This includes SP2 in your install, making it so you don't have to wait the manual install every time you decide to reinstall. Hopefully it helps someone...
Slipstreaming XP with SP2