I've recently purchased a 185GB IBM Desktar drive. I plan to add another in around a month or so to combat storage concerns for good, perhaps in a RAID formation. Quick question, I know RAID ideally requires two drives of the same size and speed. If I added another, brand say a Western Digital, that is 180 gigs ie: a few gigs less, would this make any difference to the performance of the array or would I truly be better off with two identical drives? They are both 7,200 RPM, 8 meg cache drives.