Sata II is the current standard right now and it capable of 3Gb/s. As of this moment Sata III is only on a few boards and despite being available on the upcoming Asus P6X58, there aren't many ports to take advantage of. In the example above, only two are available.
But if you are looking for speed the others have been correct by suggesting a SSD. The only downside is the expense and lack of usable storage.