The Elder Scrolls IV: Oblivion
For this test, we went with Oblivion's default "high quality" settings and augmented them with 4X antialiasing and 16X anisotropic filtering, both forced on via the cards' driver control panels. HDR lighting was enabled. Oblivion has higher quality settings than these, but the game looks pretty good with these options.

We strolled around the outside of the Leyawin city wall, as show in the picture below, and recorded frame rates with FRAPS. This area has loads of vegetation, some reflective water, and some long view distances.

The 2600 XT looks relatively strong in Oblivion, nearly catching up to the GeForce 8600 GT. The combination of strong performance scaling in CrossFire and weak scaling with SLI allows the 2600 XT CrossFire config to trounce the 8600 GT SLI setup.

On the other side of the tracks, the 2600 Pro is taking it to the GeForce 8500 GT. Meanwhile, the 2400 XT's wimpy shader core probably holds it back in this game.

Rainbow Six: Vegas
This game is notable because it's the first game we've tested based on Unreal Engine 3. As with Oblivion, we tested with FRAPS. This time, I played through a 90-second portion of the "Dante's" map in the game's Terrorist Hunt mode, with all of the game's quality options cranked. That means HDR lighting and shader-based motion-blur effects were enabled. This game's rendering engine isn't compatible with traditional multisampled AA, so we had to do without.

R6: Vegas appears to be much friendlier ground for the 2600 XT; it vaults over the 8600 GT and even the 8600 GTS. Both the 2600 Pro and the 2400 XT outrun the 8500 GT, as well. Unfortunately, CrossFire performance puts a damper on things, slowing down the Radeons while the GeForces scale comparatively well in SLI.