razer boomslang (2000 dpi model) was the most smooth and accurate mouse i've ever used - the control and fine-nudge aiming was absolutely brilliant and really made a difference... but it only has 3 buttons.
now i use a microsoft intellimouse optical and it has 5 buttons. it's acceptably accurate, and the extra buttons make the tradeoff worth it.
i've also played with, but not owned, a razer viper and found it to be every bit as good as the razer boomslang when i got used to it. it only has 3 buttons, too though.
Logitech MX510 is the best for gaming when it comes to first person shooters. Has a new optical engine that the MX300, MX500, MX700, and MX900 all do NOT have.
I tested MX700 wireless but it is a little bit heavy for me and inertia is too important.
Furthermore wireless seems to be less reactive (radio perturbations? differnt drivers?)
Now I use a MX310 with modified shape, and I feel it perfect.