The ATA133 and SATA1.5 theoretical burst rates are about the same for the drive itself, but that's totally ignoring the data bus and the way the info is received/processed. Newer technology allows more bits to be sent along 2 wires and at a faster rate than the old 16 bit (ATA) setup. That's how I read it.
And, that's assuming you have an ATA133 drive, and not a ATA100, or ATA66.