Come on, the "desperate, pathetic attempt to save face" was just a joke from HLdan. But calderone did have a point, HLdan, as he said "10.5.8+ with Wireless Mouse Software Update 1.0", and I thing 10.6.1 qualifies as "10.5.8+" and still requires the Wireless Mouse Software Update 1.0
Edit: On further inspection, I'm not entirely sure if the Update is required for 10.6.1 but Apple says so in the manual.
I didn't find it funny at all.
As far as 10.6.1, I have no doubt the mouse will pair and probably work as a generic mouse, I don't know if you will be able to customize through System Preferences or if you will be able to use the multitouch functions. It is possible that you can but since mine hasn't been delivered and I haven't come across anyone who has paired it to another machine it is tough for me to say.
But, I never said it didn't work. Which is why I said what I did to HLdan. We were talking about requirements, not whether it may or may not work without the Mouse Software Update.
Anyhow, I would like to solve the poster's problem with installing Leopard. So I will wait to see if any of my suggestions helped in, and won't be addressing this again as I have said everything that needs to be said.