Basicly the smaller cable is the only real advantage, because the drives mechanicly can't even fully utilize ata100, let alone 133 or 150. They are still 7200rpm. The WD raptor is an exception because it's 10k rpm and SATA only, but in most cases there is not much of an advantage there either. Some of the SATA II drives have some added features, 16mb cache, NCQ etc. but again, not a huge performance differance.