Neat HOW TO for keeping the mouse quieter if you have roommates . You can check recorded sound of clicking before and after. FYI, the sounds are of the Genius mouse, but the other one is dead silent too, Also the mouse buttons are now more sensitive, so you will get a few false clicks in the first couple of days, before you learn how to handle it.
http://www.abclinuxu.cz/blog/hajma/2005/3/23/81023),