I've been using the same mouse for almost over 5 years and it's USB, in fact my computer doesn't even have a PS/2 mouse port... and it's almost obsolete.
Then again I'm not one to talk, I have a G5 laser mouse but still use my MX500 optical as my main unit.
Im using some crap ass dell mouse that came with my sister in laws pc from many moons ago, and its a track ball.