F.E.A.R.
We've used FRAPS to play through a sequence in F.E.A.R. in the past, but this time around, we're using the game's built-in "test settings" benchmark for a quick, repeatable comparison.

Not only does the X1900 XT 256MB easily surpass the GeForce 7900 GT here, but it also gives the 7900 GTX a run for its money. The X1950 XT is clearly faster than the GTX, and it gains more of an edge on the X1900 XTX in this game.

The line graphs really illustrate the wickedness of that problem with performance scaling on the Radeon X1950 CrossFire setup at 1280x960. I'm not sure what the story is here. I ran these numbers multiple times, and the behavior was consistent. Must be some kind of driver quirk or something. Notice, also, that the low frame rates on the CrossFire rig aren't much higher than they are with a single X1950 XTX.