My hardware:

 P4 3.4ghz
 1.5 GB RAM
 7800 GS w/ 174 beta drivers
 

 I am having pretty bad preformance issues in games with more than 3 players. Setting my settings all the way down to their lowest doesnt do anything at all to help the low frame rate, which leads me to believe my proccessor is at fault, however I cant be sure. When I ran the demo, everything was perfectly fine at the highest settings with 3 players, but now that Im trying 4 player matches in the full version, things are just plain bad. Another differnce between the demo and full version is audio. The intro movies played perfectly fine in the demo, but now in the full version, my audio is crackly and the videos take a long time to get running.

 On another note, why are there only two resolution options in the menu?