I had to get a new mouse, because my other one just wasn't sufficiently reactive when I played Halo with my son. I would find myself facing a wall and trying to get away from him (he was trying to murder me at the time), but because my mouse was a bit worn out, I always ended up just standing there while he shot me in the back (the bloody coward).
Anyway, I went and got this one, a Kensington PilotMouse Wireless Laser. Its brilliant I tell ya. Plus, its ribbed on the sides for my pleasure.