FireFox on either Windows or Linux and you can't hear the sounds

[Tim]

On Windows, install the Windows Media Player plugin for FireFox:
http://port25.technet.com/pages/windows-media-player-firefox-plugin-download.aspx

On Linux, try installing mplayer:
http://mplayerplug-in.sourceforge.net/

On Ubuntu Linux:
http://www.debianadmin.com/install-mplayer-ubuntu.html