I'd take my 6600 anyday for overclocking potential, reliability, and stability. I hear a lot more people complain about ATI cards problems with games than nvidia. I've got my 6600 clocked past 3800 in 3d mark 05. Can run HL2 at max fine, play doom 3 at max fine, it runs LOMAC, Silent Hunter 3, WWII Online, Civ 4....everything. Very happy.