SCSI is so noisy...drives me nuts. That's when it's set up in my personal comp right in front of me though...but for a server back in some closet, who cares. I have definitely noticed greater speeds and reliability using SCSI than IDE, although it is more expensive. I personally am using IDE drives now and have never had a problem with them being unreliable (i'm not saying it doesnt happen).
I'm waiting for SerialATA prices to drop and see how others review it as it expands and bugs get worked out. SATA seems to be the way things are moving and, 'theoretically', it is much faster. (but ATA133 is also supposed to be much faster than ATA100, and that seems to be a marketing scam) SATA, within the next 10 years, will advance from 1.5 gigabits per second (equivalent to a data rate of 150MB/s), to 3.0 gigabits per second (300 MB/s), then to 6.0 gigabits per second (600 MB/s). it all sounds good. we'll see.....