May I ask exactly what this bot will do? Usually, for a bot, I would run a Atom/VIA CPU. They don't need that much computing power depending on what you do at least I haven't seen a bot using an i5. The highest computing I'v seen on a bot was on Stanley in the DARPA challenge a while back. As a robot builder, I would like to know what this bot will do. Any info is appreciated.
As for your graphics problem, just grab a cheap card like a 8400GS or so, preferably, a low profile one.