On a related note, a few weeks ago, I upgraded my PC's SSD. I had a 64GB HD (a SATA II Samsung 470 series) and wanted more room for main programs. So, I replaced it with a 128GB SATA III Samsung 830 series. YOWZAAA, is it fast! Been getting great reviews, too (along with the original 470 series).
I do highly recommend SSDs for everyone, for at least putting the OS on. You can get great deals on SATA II drives (especially 64GB drives) for this purpose. Outside of completely upgrading a 10-year old PC, I would say going from a standard HD to an SSD is probably the most significant/noticeable upgrade you could make.
Good to know about the cable difference. Although, the SATA III cables I bought were only a dollar or two more than the SATA II.
Paul