I used to buy the Intellimouse Explorer optical, the mouse was a good mouse for gaming, but I went through 3 of them in one year when I started playing counter-strike in beta 4. MS was good about sending me a new one (and they never made me send in the Junked one, which led me to believe this happened a bit with others), It would work fine for however long and then it would just slowly stop working. The light would light up and it would work for a few, then the light would flicker and go into that standby mode and not work anymore. I took my first 2 aoart to try and find the problem and the only thing I could see, was that after entering the mouse, the wire has a couple 90 degree turns in it, so I figured that after so long of gaming the strands prolly broke and weren't making good contact anymore.
The only ball mouse I would recommend would be the Razer Boomslang gaming mouse. This is a very nice mouse, a bit unorthodox to use at first, but excellent to use once you get familiar with it. The sensitivity is amazing with it, it is excellent for snipers, or picky marksman. If you move it the slightest bit, it moves with you, and doesn't skip over spots like some optical mice will do when zoomed in. Add to the fact that it has on-the-fly sensitivity adjustment, so you can adjust in game while playing, rather bring down your console. Last time my brother was up from Virginia however he "accidentally" packed it up and took it with him. So I had to find yet another mouse.
Now I use the MX500, I don't care for the extra weight that comes with battery mice, and this one is equal in every way to the MX700, save for the cord. I am extremely pleased with this mouse, and like someone else said in this thread, if you have the right drivers and it is set up right, you will not have it jump spaces (even while fully zoomed). It surprised me alot how close the sensitivity was to the boomslang in that aspect. My sensitivity is set a .3 with this mouse. Plus you have all the buttons one would want in a gaming mouse.