Well, I've been following this thread and noticed that I don't have the hideous performance that some are having. I was wondering if it was because I recently installed the release candidate of the new XP drivers from Adaptec and thinking that maybe they took it upon themselves to fix the problem.
What I did was repartition/format/install XP onto my X15-36LP w/Adaptec 29160 and benchmark every step of the way - before any windows updates, after them, after installing the new Adaptec driver, etc. All results were the same which look pretty good to me, at least for the larger transfers.
I do have my 29160 in a 64-bit (33Mhz) slot if that makes a difference.
Tyan Tiger S2460
4 10K Cheetahs (don't remember model # offhand)