I would highly reccomend the seagate barracuda ata iv line of harddrives, as would a fair chunk of people on these forums. They aren't speed demons but they can handle high pci speeds. I have 2 seagate drives now and they can easily take 40mhz and I havn't experienced any hd corruption as of yet. I know a few users on here have taken them above 45mhz without probs. I've also had great results with quantum fireball drives, however quantum has been bought out by maxtor. I've also heard maxtors can handle high pci bus frequency's.