I use a fujitsu 73gb 10k with a 29160 controller, and am extremely happy with its performance. Correct me if I am wrong, but the controller is 64bit, PCI-X type. I have heard that XP has no support for PCI-X (the slot not the card) yet, so I dont know if that is the cause. Try fdisk and then format the drive (fat32) with a good old win98 boot disk. If you are getting any nt errors, try getting into safe mode, if possible. If none still work, the last thing that I can reccomend that should work, is a good low level format using the controller's utility (ctrl+A) at bootup.