SiS don't make gaming cards. AH doesn't officially "run" with SiS cards.
Reduce screen resolution to 800x600. Turn off ALL goodies (FSAA etc) Set texture size to 128. Turn off all skins. Disable all effects. Reduce sliders 100% as far as they'll go. Then when you're in the game hit Shift F3 (short vis range). It will look like chit, but it may run.
If that doesn't help there's nothing you can do, it's a hardware deficiency.