Battlefield 2142
We tested this one with FRAPS, much like we did S.T.A.L.K.E.R. In order to get this game to present any kind of challenge to these cards, we had to turn up 16X anisotropic filtering, 4X antialiasing, and transparency supersampling (or the equivalent on the Radeons, "quality" adaptive AA). I'd have run the game at 2560x1600 resolution if it supported that display mode.

BF2142 looks gorgeous and runs well on any of these configs, but the 8800 Ultra looks best, plays best, and turns in the fastest average and low frame-rate numbers.

Half-Life 2: Episode One
This one combines high dynamic range lighting with 4X antialiasing and still has fluid frame rates at very high resolutions.

The Ultra is juuust barely edged out by a pair of Radeon X1950 XTXs in CrossFire here, but it's extremely close. The GTX again shadows the Ultra, running just behind it.