SOE tech support doesn't suck when you're buddies with the TSR. I'll PM Joel about it, something is wrong, and its not just PS. Do you have performance problems in any other games? My little brother plays on a worse system than that and gets much better performance.
I'd have to look at your dxdiag.txt to learn anything further... do you have a thread already set up in the SOE Tech forum? If so link me to it and I'll help you out.
edit- in the meantime, check out some of the links in this thread, they might help
http://psforums.station.sony.com/ps/...essage.id=5936