If you're using 2.4 kernel, edit /etc/modutils/aliases to include the kernel module for your nic, and then run "update-modules".
If you're using 2.6 kernel, the aliases file to edit is /etc/modprobe.d/aliases.
If you've got the "modconf" utility installed, that may be the easiest method to load kernel modules.
Here's another thread that discusses similar issues:
That should help you to get the network up again, but I'm not at all sure what causes your sound card problem. Did you upgrade from 2.4 kernel to 2.6 kernel? Do you have the alsa-base package installed? Enabling alsa sound requires that you run "alsaconf" (as root).
Perhaps someone can offer better advices on the sound card issue?