How to Completely Turn Off Mouse Acceleration in Windows
In this tutorial we will be turning off pointer precision in Windows. Mouse acceleration can hinder the ability to play games where you need precise aim (for example, First Person Shooters). Pointer precision, hidden in the control panel, causes your mouse to move not only based on movement, but on speed. Changing this option will make your mouse more accurate.
Go the Control Panel, select Hardware and Sound, and then Devices and Printers
Choose your mouse from the menu of devices.
Click the Pointer Options tab in the Mouse Properties window..
Uncheck the box next to Enhance pointer precision.
Click Apply, then OK. You're done!
With pointer precision disabled, mouse acceleration will be less of a problem, as your mouse movements will follow your hand movements more exactly.