You may as well stick 2 larger drives in there and backup what's required. I have 4 hard drives in my system at the mo, 2 x 120's and 2 x 160's. I also have 2 spare 40 gig drives, and 2 spare 60 gig drives. I did run 6 drives before but moved to bigger ones for the storage purposes. I'm next looking at a bigger case with lot's of drive bays and filling it with hard drives