Question about 1 button mouse

This probably isn't the greatest place to ask a mouse question, but there doesn't seem to be a mouse forum, and it is plugged into my Mini, so I guess this'll have to do.
A friend gave me a 1 button mouse (model M5769) to replace my Mighty Mouse that I broke. I plugged it in and the button works, but the side buttons don't bring up Expose. I went into Sstem Prefs/Keyboard & Mouse but the only options there are Tracking Speed and Double-Click Speed.
I searched all over the Apple Support pages but they seem to have erased all references to anything but the Mighty Mouse.
Am I missing a driver or something?