Consider the IntelliMouse Classic next time you need a mouse. Consider its 5+wheel button layout and how only three keys can be customised, if these aren't a big deal - buy it.
A 1,000Hz report rate and reliable BlueTrack laser more than offset any minor drawbacks.
Remember mouse balls?
My eyes widened when he spoke of a PS/2 connection. Sadly confusing, as it has nothing to do with this USB mouse. Why has support for the inherently much-superior PS/2 mouse connection waned so much? It's still an integral part of every motherboard in my experience.