Well, I recently bought a non-cordless (cordful? corded? cord-bearing?) optical MouseMan, and it's very nice. You'll appreciate having an optical mouse, especially if you're at the point where it seems like you have to clean your current mouse every couple days.
I'm not sure if mine is supposed to have four buttons (yeah, I know how stupid that sounds) -- I vaguely remember it being advertised as 4-button, but I didn't care as long as it had at least 3 and it didn't come in a retail box (I got a $19 price on pricewatch). Basically, it has a wheel with a typical button on each side of the wheel, and a third button where your thumb rests (it's comfortably ergonomic, BTW). Also, pressing down on the wheel counts as a button--basically, it seems to work as another third button. Being optical doesn't present any compatibility issues. Mine is USB but comes with a PS/2 attachment so I can use it as PS/2, and I just used the PS/2 MouseMan driver in X. I guess the real question for you is whether or not cordless mice have compatibility problems... that I can't answer, since I know very little about cordless mice. -- Tom "Begin by believing with all your heart that your belief is true, so that it will work for you; but then face the possibility that it is really false, so that you can accept the consequences of the belief." -John Reseck