yep as pillage said, the XP will do better, runs cooler, and has SSE. I had an AYHJA 1.4 T-bird which was its pinnacle stepping, and it did about 1.7 gigs, which was very nice at the time. However, it required some serious cooling (but its unlocked).
I would wait and see on the new XP T-bred's for lower clocked XP's. I ordered a 1700+, and I'm crossing my fingers hoping its a Rev. B.
Chiz