Firingsquad checked out the performance of NVIDIA's GeForce 8800 series in the beta of World in Conflict, an upcoming DirectX 10 game. The reason why they didn't include the Radeon HD 2900 XT in the article is because the game didn't run properly on this GPU.
Additionally, they also note that all numbers are gathered in the DirectX 9 mode as they heard from the developers that they're still heavily tweaking the game to improve the DX10 performance.
Slowly but surely the number of DX10 titles is steadily increasing. Relic was first out of the gates with a DX10 patch for Company of Heroes, followed quickly by Lost Planet. Now another RTS from developer Massive Entertainment (the minds behind the Ground Control series) is set to offer DX10 support. The game, World in Conflict, is set to debut in a little over a month and, with the highest graphics settings, it looks like it’s really going to push today’s latest systems to the max. We recently tested the public beta with a variety of high-end graphics cards to see how they’d perform with the game, we were particularly interested in the game’s DX10 path, as the game has been hyped to really deliver in this area; more on that later though.