Chipset doesnt really matter, the memory controller is on the processor. Aftermarket sales on Nvidia chipsets just went down the drain, so it took them longer/probably nagging from nvidia to slap DDR3 slots on Nvidia boards.
No that much with GTX 260s, just a few frames.
Hmm... sacrifice a few frames to save some money? Tough decision, but I think I will take the better one, those few frames can make a huge difference sometimes.
Thanks for the info though, appreciate.