Get one of the higher clocked ones and the free game. bfg's have the bigger fan after they upgraded.
YOU, YOURSELF, cannot over clock the shaders, which are upped on the faster cards.
You can overclock shaders just fine on the 8800 using rivatuner... where did you get this wacky idea? (BTW if you're using XP there's a trick to get the Shader OC'ing feature)