I am guessing by your comments, you dont have a 6600. I have a 6600 256(pic-e) and it runs every game perfectly! And its not even the gt! Dont get me wrong, I looove nvidia, not so much ati. The clock speed and pipes you just rambled off are not really that interesting to a person that is not tecnical, such as myself.
Like you said, it really comes down to preference. I prefer nvida for games and unless amd does something radical with ati, always will

Of course price drivers should come into play as well. Although, nvidia might have the price advantage, I keep hearing ati drivers cause a lot of problems. My vote goes for nvidia
