This drove me crazy for about 2 hours today. I swear I saw something in the control panel to switch between function keys and multimedia keys but alas I couldn't find it. Here's what you have to do: As the system in booting hit F2 to go to Setup. From there click 'System Configuration' then 'Function Key Behavior'. Switch to 'Fuction Key First' then hit the 'Apply' box, then 'Exit'. Now the function keys will work normaly and you can hold 'Fn' to use the multimedia fuctions.
Seriously, I searched through offline help for an hour and a half, then these forums for half an hour and I'm amazed at how hard it is to find out how to do something this simple. I'm just glad I've been messing around with computers since the days of DOS so I thought to look in the BIOS.