I've replaced my mouse with a Logitech Trackman Marble. I can now keep my eye on the cutter when I'm nudging it close to the work piece. I don't have to worry any more about the pointer drifting across the computer screen when I'm clicking the mouse. The mouse-pointer used to drift away from on-screen buttons and I had to be careful that a completely wrong button didn't get pressed. The trackball works a treat.