I have 4 hard drives in my Mac Pro 1x160Gb for the OS and 3x 250Gb. I run a recording studio and 1 disk is fine for 44.1kHz sessions but I intend to go 96kHz. I know I can set up a RAID 0 with two of the disks. Can I then set the last disk to mirror the RAID 0? Would it 'keep up'? Would the last disk need to be twice the size, 500Gb as the RAID 0 would be 500Gb, 250Gb x2 If I went for a RAID card to run say RAID 5 or probably RAID 6 I would have to get external harddrives, caddies for my drives, correct?