personally i would go with the nVidia... the new nVidia cards are futureproofed while the ATIs arent... this is just because ATI are starting to stretch their current technology while Nvidia are using new tech.
Plus the current geforce cards pee all over the ATI ones!
Not everybody is filthy rich and can afford to do this. I really want to upgrade to the 6800GT, but I just can't justify spending $400 on that right now.
On that site review, the 6800 Ultra gave them quite a few problems and error messages which I would find disheartening if I spent that much on a card. Maybe these problems have been ironed out a little now, but I am not sure.
Shadermark seemed to have a few bugs with the games. One game refused to run on the card, another would not run at full specs and prince of persia said the card was not supported *although it did run despite the message, so I guess that last one doesnt matter.
Anyway, have a look at the review if you get a spare minute!
Wow! This topic has been posted so many times just in slighty different ways. Both cards are good, both will run Doom3 on highest, HL2 on highest and whatever else on highest. rhar