Call of Duty 4: Modern Warfare
We tested Call of Duty 4 by recording a custom demo of a multiplayer gaming session and playing it back using the game's timedemo capability. We've chosen to test at display resolutions of 1280x1024, 1680x1050, and 1920x1200, which were the three most popular resolutions in our hardware survey. We generally enabled image quality enhancements like 4X antialiasing and 16X anisotropic filtering, and we also added 2560x1600 to the list for the very fastest cards, in order to really stress them. For the slower cards, we also tested at 1280x1024 with antialiasing disabled, as well.

This is a close one, but the Radeon HD 4830 is slightly faster than the 9800 GT, especially at 1280x1024 where the GPU is less of a performance constraint, possibly because AMD's graphics driver executes a little more quickly.

The big thing to take away from this test is simple: either card will run this game very acceptably at up to 1680x1050 resolution. At 1920x1200, you may have to cut back on image quality options like antialiasing a bit, especially in multiplayer.