I've been told the drives have to be identical for RAID 1, but when searching for additional drives in local stores to match:
WD 1TB Caviar Black 7200rpm SATAII w/ 32MB Cache
They say they don't carry those anymore but they do have the same drive w/ 64MB Cache instead. They also told me that RAID 5 was not as finicky as RAID 1 and that it would probably be fine to use the combination of 3 drives with 1 having 32MB cache and 2 having 64MB cache.
Does anyone know this to be true? Does cache have to match when doing RAID 5?