Best value

Hi. I am planning a build and was wondering about the graphics card. so far, I have narrowed it down to two choices: an ASUS Direct CU II 7950 @ 900Mhz for 350$, or an EVGA gtx 670 @ 915Mhz (stock clocks and stock cooling) for 440$. I can go with other manufacturers but the pricing is similar. 300-350$ for 7950 with aftermarket cooling, and 400-450 for gtx 670 with stock cooling. I can and will overclock, and have a case with good airflow. I will probably expand to a dual gpu config so take into account SLI/Crossfire scaling for these cards. also, im pretty sure EVGA's customer support is unmatched so thats another plus for them. The question is this: $100 is not little money for me and I only want to spend it if its worth it. Should i shell out the extra 100 for the performance bump given all the *** i just said?
thanks