Ok, so you've got all the needed modules, none are loaded which isn't surprising with no soundcard detected.
If alsa doesn't detect (and even less support) your sound card you have to upgrade your kernel, there's no point loosing time fiddling with modprobe.d and so.
You can either download the kernel and eventually necessary dependencies from Etch-backport (try
here, end of the list for etch-backport) or add the right repository to your source.list.
You'd better stick to etch-backport if you want to stay with "Stable", if you try installing Lenny's kernel you'd better go entirely for Lenny since I think you will have to upgrade important packages (libc6, gcc...).
If your card is supported by the 2.6.22 alsa then installing it and calling "alsaconf" should do the trick.