If it's for a webserver, just throw in a 3ware card and a couple matching UDMA drives, and run RAID 1.
figure $150 extra for the drives, and $250 for the card.
Better performance than a 2 disk SCSI RAID1 mirror. no matter what people will try to tell you. SCSI is starting to offer no real advantages other than disk density (i.e. 15 drives per controller) and very fast random access speeds (15k rpm drives). For small RAID setups, all you get is set back some in cost, for most likely less performance.
I used to be a die-hard SCSI fanboy too.
Of course, there are times that SCSI makes very good sense.
-Phil