i have gone to optical mice--i have a cat and it was driving me nuts trying to keep it clean. THEY WORK GREAT. i have been using cheap ones, they have been killed-probably by the cat(kitten). it doesn't appear to be the mouse itself, but the cord. but i'm using like $7.99 specials. and they hit the floor at least once a day.
i had to use a ball mouse for a day last month--GO OPTICAL