This works best with "How to speed up mouse tracking in OS X", found elsewhere in this forum. Note that mouse acceleration in OS X cannot be terminated completely, unless you are using something like USB OVerdrive. Assuming you are not using or do not want to use USB overdrive or similarly complete solution, read on. Download the source here: http://forums3.armagetronad.net/download/file.php?id=9698 You'll get a Unix executable file. Open a Terminal window and drop the file onto it. After "killmouseaccel", type "mouse" (without quotation marks), and make sure a space remains between the two words. Then hit enter. Effect is immediate. Logging out or restarting will kill the effect, so you'll have to run it each time. You might be able to set it to an automatic script upon logging in. Something I haven't figured out yet. Ideally, it's best to increase the mouse tracking speed first (using instructions I posted elsewhere in this forum), which should be permanent until you reset the speed in the actual mouse pref pane, and then run the executable to kill mouse acceleration.