Check the BIOS to see how the drives are configured - ie. AHCI, RAID, or IDE. That might be the problem. They need to be set to AHCI or RAID before doing the install. You can't change this after the OS install very easily without issues. I have a Velociraptor 150, Seagate 750, Seagate 320 and a WD 640 (all SATA 3.0) that all show up fine. I have the BIOS set to RAID but am not currently running anything in RAID yet.