Changing the Video settings

I'm not much of a PC gamer anymore, so my rig is pretty old and outdated.
Pentium 4 3.0Ghz
1Gb RAM
Nvidia GeForce 6800GT 256Mb
Anyway, i've been playing Halo 2 on Low settings with AA turned off, just through the single player campaign.
I have noticed slowdowns when coming upon batches of covenant and whatnot. And there is a lot of slowdown in the cut-scenes at times which overall screws it up. Anyway, i just want the game to run smoothly before i jump into multi-player, and graphics don't matter to me, so i was wondering is there anyway to lower the settings even further? I mean, is there a way to change some files? or a mod or anything!?
Thanks.
Oh, and any recommendations about what would help the performance? Is my RAM the first thing i should upgrade?

In my experience, there really hasn't been much of a noticeable difference in framerate between high and low. I noticed a max of 6 FPS, which is awful and is due to how much of a suck-ass professional job Hired Gun did at porting and optimizing the game engine.

What screen resolution are you running at? Since you have a 17" monitor, if you're running at 1280x1024, try bringing it down a notch to 1024x768. Hopefully you will be able to increase your framerate 6-10 FPS average, but that could also be pushing it due to the number of bottlenecks the game creates on itself.

Other than that, I'm sorry to tell you that there's essentially nothing you can do to increase your framerate unless you were to drop some dough on some new computer hardware. As you can tell, there's next to no video settings to alter, and to make it even worse, these geniuses thought it would be SO cool to not even provide a cfg file to allow the more advanced users to manually tweak the video settings.

I run the resolution at 800x600, which is what it automatically went to when i installed the game. I guess thats pretty bad. Ill look for some RAM then.
Thanks for your help.

http://www.crucial.com/