Updating my System, i have a GTX 580 SC 1536MB GDDR5, a price of a new one is roughly 400$. I don't know what to do i'm out of date with all the new hardware out and i cannot keep up. I Know that the gtx 660 and gtx 760 are roughly 200-250$ each would it be better to get two of them to sli instead of getting another gtx 580? or should i skip think a upgrade to a single gpu somewhere in the 600-700 series help, thanks - paul.