"Downgrading" to XP

Well, I'm finally tired of trying to use Vista on my QuadCore. I keep on finding my new computer randomly doing things where it suddenly goes crazy for 20 minutes and is dog slow while Vista is doing some sort of disk indexing or other craziness that I haven't yet figured out how to turn off. XP just seems faster and snappier -- my old computer with XP seems faster than the new QuadCore with Vista. Plus XP works well with all the programs I use and I don't want to spend a couple hundred upgrading Ghost and VMWare and other reliable standby software that I own that isn't Vista ready. I'm going to keep the HD Vista came on just in case I want to play with DX10 but for my daily use, I'm sticking with XP.