As root, do the following:
When it asks if you want to look at the card database, say 'y'.
Use the i810 driver - I think it's #15.
Make sure that your monitor refresh rates and Horiz Sync are correct.
If in doubt, use a lower rate.
Try 31.5 for Sync, and 50-70Hz for refresh rate.
Startx again, and you should be fine.
If not, post the output here, along with /etc/X11/XF86Config.
It should say "Screens found, but none have a usable configuration."
Good Luck