Well, there is no magic mouse. However, finding one that suits you can definitely make a difference. I can't stand those new molded stlye mice. I prefer using a traditional plain vanilla mouse, so I've been stuck with a ball mouse for years. Also don't want wireless.
Finally, I find out about the Logitech G3 which is laser, wired, and is the old school style. So I've gotten more accurate in CS:S and the side button set to "swap weapons" gives me a solid one second jump on most other players when switching to pistol. I don't really use the high sentitivity settings as I like greater control. Wouldn't make a great player out of a lousy one, but definitely gets some obstacles out of your way as you start getting really good.