Re: problems with installation
Try manually selecting the forcedeth (nVidia) network card from the list on the sarge CD.
I had a similar problem with my Gigabyte motherbard, which has an nForce4 chipset. I used the AMD64 Sarge netboot CD, and it wouldn't automagically detect my network card, I manually selected the forcedeth card and the module loaded, no complaints.
As for sound, I believe after I had everything up and running I had to apt-get all the alsa stuff and then used module-assistant to get my sound up and running.