I used a wireless optical Intellimouse for about 1 year. It started getting old in FPS (namely BF: Desert Combat and the such) and so I went and bought a 10-buck wired ball mouse. I won 7 matches in a row in Desert Combat that night.

It was like I was on a handicap or something. Sorta like Goku training in 10X gravity (for all you DBZ fans). I'm never going back to wireless optical.