Originally Posted By: Dignan
I think it's pretty clear that the middle mouse button is the least used, so I don't want a mouse that gives equal space to that button.

Under MSWindows, maybe, but under X-Windows (that is, Unix), it's very important. The left (and often the right) button is used to select text and the middle button is used to paste. There are various ways around this, but the default is to press on the scroll wheel, which, as Tony points out, is incredibly fiddly.
_________________________
Bitt Faulk