A few questions..
What's the performance difference when using an onboard RAID chip as opposed to a dedicated RAID card?
If he's RAID 5'ing two 320Gb drives, would a 640Gb F1 be the best choice as the third drive, as that wouldn't waste any space surely?
If he does get a disk failure, to recover the data does he remove all the disks from the RAID and plug the 640 say back straight into his mobo? Would that boot?