[RyanCahoon]

If you're worried about the price limit and weight, you shouldn't even be looking at laptops. Build your own Mini-ITX board. You can buy/bill the components separately and to your needed specifications, and that way you don't have to carry around the screen. There are power supplies on that site designed for car computers that are tolerant to voltage drop-out as well, so you can even power the computer off of the robot's battery, saving you more weight.