I have a Hitachi 320GB 7200 RPM 8MB Cache IDE Ultra ATA133 via usb 2.0
In the words of the Mythbusters:Well there's your problem ...
USB 2.0 will limit any hard drive to about 28 MB/sec maximum.
IDE/PATA drive connected directly to a IDE/PATA interface will perform nearly identically to a SATA drive of the same model. Hard drives these days have maximum transfer rates that do not approach the bandwidth that either interface is capable of delivering.
IDE is capable of 100MB/sec (133MB/sec in some cases), SATA is capable of 150MB/sec minimum, 300MB/sec in modern implementations. Consumer hard drives all run in the 60MB/sec to 80MB/sec range, well within all interface capabilities.