Mikhailtech has reviewed the Microsoft IntelliMouse Optical, I'm using the same mouse for almost 2 years and it's really a very good mouse ! Here's a snip from his review :
For some reason the past few months my trusty Logitech wheel mouse has been giving me trouble; perhaps a piece of hand salsa found its way into a corner beyond my reach. Whatever the cause, it froze up at very inopportune moments. Using a wheel also meant lower sampling rates and a limited surface availability. That's not to say an optical will work in any environment, but you're not held back as much. Microsoft's IntelliMouse Optical is a very well designed mouse. It's not too light (hollow like the Mitsumi I reviewed not too long ago) or too heavy like wireless battery-laden parts.
It feels pretty natural and it took me surprisingly little time to get used to it. My only complaint is the sensitivity of the side buttons. It's incredibly easy to accidentally depress them when browsing through sites or folders since your fingers do rest there. There's really no way to disable them aside from installing generic drivers or using the PS2 interface (same thing). And seeing as how I don't use them much anyway, I like mine turned off. But the option is there for those who want their money's worth.