Thanks, you've confirmed what I was expecting. Even tough, I asked about that because my motherboard (Asus Crosshair IV Formula) has six SATA III connectors versus a single SATA II connector and, in addition, they are much better placed.
On the other hand, I've heard that "normal" HDD's like mine don't take profit of the total available bandwith even with SATA II connection. So, my intention is to connect my HDD to a SATA III port using a SATA III (or SATA II?) cable.