first off, you can't use Windows XP with pro tools.. well not yet. i have a fairly similar setup as what you want, and i've tried it with pro tools free. it worked, except each track would be out of sync with the next track, and i'd have to manually line up each track. appaerantly, this is only a PTFree problem, and it sounds like this is fixed in their full version. But your system sounds awesome. It also helps if you keep your disks defragged, and optimize windows by cutting out all the crap you don't need, there's various articles around here on how to optimize your PC for audio recording.