I agree that muting your sound is the best approach.
The preference pane you found RobertC looks a little dangerous to me. It doesn't appear to be Leopard aware, and was released in 2007, so any late model Macs (the new Mac Pro, the new iMac, the latest MacBook/Pro revisions may all not be well tested or working properly. I guess this is a "use at your own risk" warning.