I just started mining with 6 - 7950's in windows 7 x64. Was using guiminer at first, but guiminer wasn't using the cards full potential. I downloaded a copy of cgminer, and was surpprised at how easy it was to make work. I have MSI twin frozone III cards which are overclockable. With a common box house fan pointing at them, they run at about 570 gh/s and 70 - 72 c.