With my laptop, I use a Magic Mouse at work and a Logitech mouse at home. With the same "tracking speed" configuration on the Preferences, the Logitech moves much faster, which forces me to change the tracking speed every time I switch between the Magic Mouse and the Logitech mouse.
Is there a way to setup a different "tracking speed" depending on the mouse that is connected, maybe through a third-party utility that works with Snow Leopard?