No sound after W7 32bits install iMac G5

[Entrix]

Hi there,

First of all thanks for reading this, I'm in big trouble.
I've just installed W7 32 bits on my iMac G5 2006 and the sound doesn't work anymore for the windows part.
When I boot the computer, before it gets on Windows, there is the chime going on and then, no more sound.
I've tryied to uninstall the sound driver and update it, but nothing.
I can controll the sound with my apple keyboard.
Tryed with internal & exernal speaker + headphones, but nothing will work.

Any idea?

Thanks a lot

-Entrix