This is first time I had to reinstall this computer (year and half). The old one was often reinstalled (win98/2k dual boot) as there was no registration problems, but Xp is much more stable for me then any other micro$oft OS, so there was no need for reinstall.
Thing that I liked is that I was able to install XP with SP2 already applied. That makes it much easier. Also it was about the time to check all the drivers.