Some Intel onboard VGAs have an open-source driver. I don't know if i830 is supported by this open-source driver.
I don't have an Intel onboard VGA, so I can't say with certainity, but I see a package named:
it may be it! Give it a try. Don't ask me what to put in Xorg though :-P
If this doesn't work, or if you want something temporary to work for now, you can try the "vesa" driver.