[illunious]

One possible problem: When using your mouse, you should use your elbow as a pivot point, not your wrist. Your wrist should be floating and moving with your arm, not sitting on your desk rotating. This is not an easy habit to break, but if you find that it's what your doing you should try to break it.

I use an Aeron chair (if you haven't tried one, I highly recommend it). It has a great adjustable arm rest and I set it slightly above the level of the mouse pad. When I'm using the mouse, my elbow is always resting in one spot on the arm-rest. When I move the cursor from left to right I am moving my entire forearm left-right. Up-down and small mouse adjustments are done with my fingers.

Another thing to try would be increasing your mouse sensitivity. If it is set really low you are moving the mouse more than you need to.