Well i agree with sky .... at least on the single card thing there pretty even.
And anytime someone try's to say the nvidia drivers are some "better" I disagree with it cause they do screw up, like how about awhile ago there driver killing cards cause it actualy shut off the fan's on there cards


. Also as tom's proved a few years back, there driver/software preformance is dependant on cpu speed/accelorated where as ati/amd's are not dependant on it.
I also still think that while nvidia has improved on there image quality n such. I always found there graphics to be "blocky" & "bright". I always found ati/amd had vividness/depth in there rendering vs nvidia's & im the type of person that would rather have a quality image vs blocky/jagged images + higher frames.