slow performance 82801fr driver

I have a Dell XPS Gen 3 with a 82801FR Intel controller. I have it set up to RAID 0 with two SATA drives. Vista Beta 2 installed fine with the latest drivers off the Intel site, however, performance is SLOW, SLOW, SLOW.
I checked in the performance CPL and it shows the disk performance at 3.1. It should be much higher, I think. I can tell a big difference, between local disk operations and network operations. HD light is on CONSTANTLY. I thought perhaps it was SuperFetch or Index working overtime, but I turned those off and it still was constantly being accessed. I also checked to see if any other drivers were slowing things down. It doesn't appear to be the case, but it is possible.
I don't know what to do, but it really makes Vista hard to use. Are there beta drivers available for Vista for this controller anywhere? If so, I can't find them. Does anyone have any other suggestions on how to troubleshoot?