Vista and XP have a default USB polling rate of 125hz, which is not optimal for smooth scrolling within fast paced games like Counter-Strike. For more info on polling rates, visit here.

This great little app allows you to change the polling rate from 125hz to 250, 500, or 1000Hz. If the engine of your mouse is capable of taking avantage of such speeds, it will boost the performance of your mouse.

Try using the "testHz" button to see what your polling rate is before using USBRate then set it to 500 Hz. Test it again to see if your mouse can benefit.