Awesome thread!
In my mousing experience i've gone back and forth b/w logitech and microsoft over the years. Both companies have made some very fine rodents.
Waay back in the day (during Warcraft II's heyday) I used a three button logitech mouse that was beige (or white) and shaped like a diamond. Man, was that the most comfortable mouse ever, or what? Later on I heard that Thresh of Quake fame was using a Microsoft Intellimouse,just like the previous poster said it was the old one with a ball, two buttons and a scroll wheel, so I gave that one a try and liked it very much.
A little while later I used an early logitech two button optical mouse, which was awesome, but it didn't seem to have enough countour to it for comfortable long term use, so I switched to the Microsoft Intellimouse Explorer 3.0, which I felt was the best gaming mouse of all time, hands down.
Eventually however it went batty due to too many reloaded thompson clips in DoD, so I upgraded to the MS Intellimouse Explorer 4.0, which I've been using ever since. This mouse is pretty good - I was suprised how naturally it fit to my palm and fingers straight out of the box. My only complaint is the smooth scroll wheel. Without tactile clicks, changing weapons in 1st person shooters is nigh impossible to do fluidly.
With that in mind I finally succumbed to the hype and bought a Logitech G5 mouse. It's a very interesting mouse, tons of options to play with, and a very interesting color scheme. I found it a bit odd to use after so many years with an MS mouse. I wonder how long I should give it to get used to this mouse?
Also, my little bro uses the Dell two button optical (made by logitech, maybe?) which is suprisingly nice feeling.