You don't need a U320 adaptor for a single drive. Even the fastest SCSI drive on the market cannot exceed the limits of an Ultra2 (80MB/s) bus. Save your money and get a U2 or U160 controller. I have used both Adaptec and LSI onboard U160 controllers with 5.6 and they both fine. LSI is my preferred choice for performance but the BIOS utility is a bit spartan.