FGBullet, like Chalenge I'm not up on AMD cpu's. The clock rate looks ok, but I don't know if the game can use all of its cores. You should be able to check it in the Task Manager when the game is running (Alt+Tab out of the game, right click the Task Bar, choose Task Manager).
Another thing I noticed that your Page File usage is on the high side. That often means you have a lot of background processes running and consuming your RAM. 4 GB is on the edge of being enough but you might find doubling it worth the investment (if your motherboard can take it, and I believe it should).
So, if your CPU only uses one core for AH and you have a lot of background activity further stressing it, it just may be possible that your video card can't get enough information to work at its best.