You did load the SiS 900 LAN driver, didn't you? And you also did enable "Onboard LAN" in BIOS?
Sound is an SiS 7012 engine, currently not yet supported in ALSA but supported by kernel sound drivers. The analog conversion and volume control is done by a Realtek ALC100 codec, which is also supported.
Can't say more, since my Linux-on-K7S5A project isn't yet assembled physically.
regards, Peter