You need to find a demo (or make one yourself) that runs on the version you have (demos normally only work on the version they were created with). Then you go into the Multi-Player version. Go into the council (type ~). Type timedemo 1. Then type demo followed by the name of the demo. It will run the demo as fast as it can. Go back into the council and read what it reports in FPS (frames per second). I used to use a demo called check-point, but then I downloaded a partch/update so it does not work any more.
AMD Phenom II x4 945 3Ghz | ASUS M4A77TD | 2X WD 1TB SATA 2 hard drive | 2x2GB Corsair XMS3 | nVidia GeForce 8800 GTS | ATI TV Wonder Theater Pro 550 | Antec P-160 case | Antec 650w Earth Watts | LG Blu-ray Super Drive | LG DVD RW | Windows 7 Pro