Secondary Hard-drive for Mac Pro

[uMac]

Okay, I have a Mac Pro with only One Drive it in (250GB).
I am looking for another drive (in the 250 - 320 range) does it need to be SATA or SATA II?

It will be used for Time Machine (which I've heard Rocks).

 

[Cave Man]

For a Time Machine drive, I don't think it'd be all that important. Just get the best deal that fits into your machine.