The Ultra-160 drives should be the fastest way to go, though, it is questionable if they are worth the price difference on anything but a file server, though. However, when I was doing some Video capture a couple of years ago I was very impressed with the speed of SCSI (4?) drives compared to ATA-66 drives that were "supposed" to be almost as fast. It was day and night. I'm under the impression that a lot of PC people have ATA 66 drives running at 33, and ATA-100 drives running at 66 because they don't have the right cables (for the 100) or drivers installed, incidently. There is also a new ATA-133 spec that is starting to surface.