Quake 4 Low FPS

I reinstalled this game yesterday, and am now playing it at 1920x1080. Once I cranked up the AA to even 4x (let alone 8x, 16x), it's drastically slower than it was when it was running on my 1680x1050 monitor. An 8800gts with 640mb's of RAM should be able to run this game smoothly at higher resolutions, no? When I was outside of the bunker at the beginning of the game (and the whole intro sequence, for that matter), it was pretty much a slide show. Once inside, it was better, but still rough. In regards to patches, I've only installed the 41.4.2 update. Should I be installing all of the previous patches as well? I don't see any reason why this game should bog down this much. Is there a setting on the 8800 that needs to be adjusted? I know it's five years old, and you're all probably wondering why I'm concerned, but I certainly appreciate any suggestions.

Thanks,
Brandon