Turning off vsync, however, will make your graphics look like crap. If you like your screen to jaggy up every time you move and don't mind dealing with lines across it, by all means turn it off. Otherwise you might consider getting a fix for winxp. XP has some stupid built in thing that drops your refresh rate to 60hz whenever you start a game. Ugh.
If you've got an nvidia card, there's a built in fix in the latest drivers, just go into the video properties and the advanced area and look around and you'll find it. For ATI, I forget where it's at, but it's probably in a similar location. Set the fix refresh to whatever your monitor can handle. (I'm not taking responsibility if you try and go over and your monitor explodes) Mine's set to 75hz, so I get a max of 75 fps and it still looks good. Turning off vsync so you can up the fps is just a bad idea, this way works much better.