guessing that these 'other parts' are the parts where there is alot of action in them. General performance settings will help out (lower sound to 22Mhz, return to Normal filtering, lower the window size).....does this choppiness also happen with other games too?
just because you paid a thousand bucks, doesn't mean it's a top-of-the-line PC
just because you paid a thousand bucks, doesn't mean it's a top-of-the-line PC