[quote name='kakomu']Those are theoretical speeds. From what I've seen, most 7200RPM drives perform approximately the same right now.[/QUOTE]
This is absolutely true. For example, current tests of several of the known fastest IDE hard drives show they top out around 70MB/s in sequential reads. This isn't even close to the maximum speeds. Not sure about Serial ATA, but Parallel ATA can only access one device at a time, so you can't even read two drives at once to saturate the link.