Bootcamp Win7: no audio on Macbook

[rightlyso]

I installed Windows 7 and Bootcamp (Leopard) on my brother's late model White Macbook. Everything SEEMED ok, but now he tells me there is no sound. I don't have the laptop with me, but I had him dig through the installed drivers, and it seems there is a driver installed for the external audio jack, but no driver installed for internal speakers. Any ideas on how to fix this? Can he take it to the Apple Store?

[rightlyso]

I checked out the laptop myself, and still no luck. The speaker driver seems to be installed, but no sound comes out of the internal speakers.