If vsync is enabled (by default it is) then your max fps is the refresh rate of your monitor. Turning off vsync allows the video card to render frames as fast as it can do so.
I recommend leaving vsync on though, there are some games (AH was one at one time) where disabling vsync resulted in problems. It's also worth noting that your true frame rate is still not over the refresh rate of your monitor. Only parts of the screen are being refreshed at any given time when vsync is off. The only time you should turn off vsync is for benchmarking IMO.
The 60Hz refresh rate is a common issue with Windows 2000/XP. In windows 2000 you can sometimes work around the problem by going to run and typing "dxdiag". After a short time a window will pop up. Select "more help" and then click the override button. Input an override value of 75 or 85 Hz, restart, and try it.
There is also a patch available that does the same from 3rd parties.