I've heard turning off mouse acceleration can help precision in games. How do I do this in Windows XP?
Open Mouse Properties, and on the Pointer Options tab, look for "Select a pointer speed", then the "Enhance pointer precision" checkbox.
Turning it in the mouse settings will actually only effect cursor on the desktop. 3D Games ignore that setting.
To turn off mouse acceleration in games you need to edit the registry.
Luckily, there are comfortable tools that do this for you. Note that this works also on Windows Vista and 7.