I use an MX500 since it came out on my 5620 and I game frequently. What I like most about this one is how it fits smoothly in my hand. The Xplorer is a bit more bulky which I used before this one came out. There is no chance you will be able to distort the MX500 by swinging it over your desk.
However, Logitech Mouseware discontinued game support with the release of version 9.77 or something. So either just install the drivers and not mouseware or stick with 9.73 (I do that).
Also, you will not be able to use ALL the buttons in the game. I use all but 2 on it because I personally did not find reliable keys to bind them too.
Intellipoint, the software with MS mice, is far superior since it lets you bind different keys depending on which program you use. That is damn great! Furthermore all buttons on that one work in game (Xplorer (get the latest version (3.0)).
Still, I can survive with mouseware

, and the MX500 is a very nice mouse with smooth control precision which is what you need in games. (use PS/2 port since you can oc that to 200hz instead of usb (125?hz)
Edit: Ack! I was just surfing logitech and check their latest drivers and VOILA: Advanced Gamer utility? o_O
http://www.logitech.com/index.cfm?co...alldocuments=0
:|