OK. One last try.
$ ls /lib/modules/(uname -r)/kernel/sound/pci/snd-intel8x0*
(I think you know what to replace (uname -r) with).
Assuming you come up with a couple modules there ...
Create a file named /etc/modprobe.d/sound with this:
alias snd-card-0 snd-intel8x0
options snd-intel8x0 index=0
Reboot and see if a miracle occurred.
If that fails, my advice is to reinstall using Debian 'testing' (etch) instead of 'stable' (sarge). Testing, is much more likely to include support for newer hardware. You may want to try getting another opinion about that, tho.
If you elect to reinstall, go to http://www.debian.org/devel/debian-installer/
and get the netinst .iso (about 100 mb) for your hardware
After the base installation, you get to select from groups of packages defined as a 'task'. Several tasks are offered. Select only the 'Desktop'. You can get other stuff later.
The installation will include kernel 2.6.12. I would go ahead and update to kernel 2.6.15.(whatever)
# apt-cache search 2.6.15 --names-only
Find the right one
# apt-get install linux-image-2.6.15.(whatever)
# apt-get install linux-headers-2.6.15.(whatever)
While you're there, you may also wish to pick up the nvidia modules, or whatever else looks important.
# apt-get install alsa-base
# apt-get install alsa-utils
That's my best shot ... Sorry I can't just magically make it work.