I would still get the best one offered and that is the SATA II. The DFI motherboards all use the same chipset with some supporting SLi depending if you want to go that route. They look all the same to me, just different names. I notice storage support is a bit different as some support SATA II while the other model supports SATA I. Onboard sound differes with Realtek and AC97 Codec. Some have more USB support and more integrated Ethernet port than others. It comes down to matter of preference of what you want. The more expensive the motherboard are, the more features it supports generally. Do you want SLi support? If so, this is a good one:
DFI LANPARTY nF4 SLI-DR Socket 939 NVIDIA nForce4 SLI ATX AMD Motherboard - Retai
It's got an extra RAID controller, and support for all kinds of hard drives. This motherboard is totally loaded with stuff.