You probably need to install the sound drivers from Nvidia: http://www.nvidia.com/object/linux_nforce_1.0-0310.html
If you notice at the top of the page it mentions that the latest version adds support for nforce 410 motherboards.
To get it to install, you may need to recompile your kernel or at the least install kernel headers for your kernel. You can try installing the kernel headers with:
apt-get install linux-headers-$(uname -r)
Then try running the Nvidia nforce installer. If it fails to run, you may need to install the kernel source and recompile your kernel. There is a guide to doing that here: http://www.linuxquestions.org/questi...d.php?t=206992
I wrote it a long time ago, but it still shows what is basically involved. You can install the latest kernel source with:
apt-get install linux-source-2.6.15