I haven't built a SiS chipset based system and I don't know if Linux drivers are available for them. Generally SiS chipsets are fairly reliable, but tend to lag somewhat in performance behind other chipsets available.
I have used nForce based boards recently, and there are Linux drivers for them at nVidia's site (though I haven't tried Linux on them). If the drivers work correctly under Linux you can build a very inexpensive system with the 420D chipsets with integrated GF 2 Mx, great onboard sound, and often integrated ethernet as well. My current system uses the Asus A7N266-C board, which uses the 415 chipset. This means it does not have the onboard video and this particular board does not have integrated ethernet either.