The ones with the 5.x access times? (Can't remember exact number, but they run HOT.) Those must have set you back. Are they on the same RAID controller?
Two are raided and two are not. :-) I am using the ICH5R south bridge. They are two Western Digital WD2500 250G SATA drives and two Maxtor DiamondMax Plus 9 250G SATA drives. I use an IDE 133 200G Maxtor drive as well for my boot and C-drive.