Are those the only motherboards available in your area or something? Because Intel's new P45 chipset is already out. I recommend going P45 just in case future cards actually need the full bandwidth needed from PCI-E 2.0.
If your willing to spend that much on a motherboard then you might want to look into the P5E Deluxe X48. I've seen a couple of reviews saying that this is a pretty good oc board also.