lloyd: Take a bit of time to format you posts, please?
In some games, there may be some features (often shadows) that may be pushed onto the CPU rather than the GPU. It often helps to set the game to the bare minimum settings and slowly turn up the settings until it slows down, so you can figure out what setting(s) is causing the trouble.
The best thing to do is to find the bottleneck. Find that one resource that is maxed out. You mentioned that the CPU is at 30%, and you're running a quad core system - open Task Manager and check the individual cores - if one is maxed and the others aren't, then that's your problem.
Captain and Screet: It's entirely possible for something to be multithreaded, yet to have one thread take up more CPU than the other threads. Being able to use multiple cores doens't always mean you use them equally.
This is an odd problem, though - if he's running at 3.2 GHz, then that should be more than plenty even with a single core.