The current MS Mouse drivers work fine for my IntelliMouse Explorer. The only problem I have is that when it's installed, the "Ignore Trackpad when mouse is present" mouse preference on my iBook does not work! I'm not sure if this is a MS problem since the same thing happens when I install the Kensington mouse drivers.
The bottom line for me is that installing a 3rd party driver kills this functionality. I wish Apple/MS/Kensington would fix this ASAP. Other than that, I have no trouble out of the MS drivers at all.
OAW