One of the best softwares I have used so far for those little clean jobs to make your xp faster.
This isn't a system cleaner like those other softwares that get rid of your junk files or bad registry entries.

http://www.nliteos.com/

Microsoft XP Professional Install CD is about 600meg. It includes alot of services and junk that most of you won't ever need and some that you will. The more processes and components means more cpu usage and more memory usage. By using nlite you can eliminate those uneeded components and embed sp3 into your xp install CD. And when you boot to that CD and install ms windows xp on your computer it will be faster and less of a resource hog than before.

I have customized mine and I was able to get it down to 144Meg iso. After installing cpu process stayed very low and memory usage usually stayed below 100meg (out of 3Gig total available).

Try it out yourself. You could even try installing inide a virtual machine to see the result of its resource usage. (Vmware - not free unless you get player which is useless if you want to try installing xp) or you can try (QEMUmanager - comes with QEMU and is free solution to being able to create your own virtual machines with Microsoft Windows XP)