Either you should choose the correct driver with supported resolution of 1280x800 of widescreen,
Or, try some generic driver that gives you the resolution of 1280x800. That should work.
If you don't have 1280x800 at all, then 1280x1207 should work too. (Wait, I can't remember exactly 1207 or 1270, you should check it out and see... sorry, it goes blank on me).
Hope it helps.
-van.