Dude i hv an nVIDIA GE Force FX 5200 (256 MB DDR RAM) graphics card on an intel D865 GBF mobo with 256 MB DDR RAM (266 Mhz) and 40 GB HDD, but the game runs smooth like a butter on my System
In the graphics options,ry lowering the Antialiasing and other graphics rich options, slao tyr running the game at 800x600 resolution,U will hv to personally and manually figure it out wich settings work for ur system...
ALso make sure no backgroung tasks r running like an antivirus scan or a firewall or even a wallpaper.
Do post in ur results after doin sum troubleshoooting by urself on the game...
cheers n peace.....