As noted above, a single 7800GTX 512 has little problem running this game at high resolution getting around 40fps on average at 2xAA 8xAF and maximum detail settings. You are going to need a pretty hefty system to get CODII running. However, there are some life savers for those of you with less well endowed setups. For really old graphics cards, there is DX7 mode, which while making the game look more like Call of Duty 1 by losing all the fancy DX9 features, improves performance no end to the point where most reasonable modern cards should be able to run it in some form. Also, complete manual configuration of textures is available, although again, dropping these too low will really hinder one of the engines nicest looking features.
DX7 - DirectX 7 Light versus DirectX 9 Light
DX9 - DX9 Lighting is much more subtle, also note ground textures, but DX7 mode can be a life saver for older GPU's.
One final tip for those of you with an SLI configuration of some sort. You need to manually enable the optimise for SLI option in the games menu in order to get the best fps out of the game. However, rather annoyingly this resets itself to NO every time you restart the game. To avoid this problem, you can add the command +set r_multigpu 1 to the command line of your desktop shortcut so it automatically enables it every time you load the game. This means your target should read "C:Program FilesActivisionCall of Duty 2CoD2SP_s.exe" +set r_multigpu 1 providing the game is installed on your C: Drive. Next we come to sound. Now, the Call of Duty series has to be the noisiest gaming series ever. COD II meanwhile is one of the few games that I would seriously recommend you beg steal and borrow a decent set of 5.1 surround speakers for, shut yourself in a soundproofed room and whack the volume right up as far as you can bare.
To say that the sound in COD II is immersive is an understatement. The sounds of the battlefield are reproduced in a glorious and deafening cacophony of sound from the endless hammering of machine guns, to explosions and the screams and shouts of soldiers on the battlefield fighting to the death. This game really is one of the few where literally 50% of the immersion comes purely from the sound, and the quality of the games sound effects is virtually as important as the game engine itself. If you have armed your PC with a half decent sound card, this is the game to use it on. Its truly remarkable to hear, and will have you catching your breath and sighing with relief as you try to re-gather yourself when ever there is a pause in the action.