I just did a clean install with Vista over my XP and it worked pretty good, my PC is definitely faster and other than a few driver glitches it is still doing good after two weeks. The speed may be attributed to all the junk being removed but I don't think so. Vista has rated my PC perfromance at 3.4 and that's not to bad I guess. I am not going to run out and change my cpu and motherboard for a few nanoseconds.
It almost sounds like a HP problem, I ran a Vista compatibilty test 1st and that helped me make the decision plus I was bored and love to reload all my programs on the weekend.

Mukk mafi