I'm with you, my specs are nearly the same as yours. The graphics are pretty sad and I've encountered a weird bug that makes my character walk forward without me having to press any keys, so I start a game and he/she walks straight ahead whether I like it or not.
IMPORTANT EDIT
My game looked like shit and I wasn't happy, my system rocks so that it was a rip-off, further tinkering and I found that "Force Object LOD" was on in the games graphics panel, TURN IT OFF, it will boost the beauty of the graphics incedibly. It also fixed my annoying walk problem.
Still not satisfied, then get the performance boosting patch here:
http://www.fileplanet.com/files/120000/123863.shtml