Gertbot is a daughter board for the Raspberry Pi/ I'm going to use one of the original raspberry Pi for the board. Gertbot plugs directly to the GPIO. On the back is a nice diagram showing you how to connect the motors and power supply. It's purpose will be to control the motors.
There is also built in thermal and short-circuit protection. I will be using Python scripts to control the CrowBot from my Blackberry.
I'm uncertain if this chassis is too big. There is plenty of room for multiple Raspberry Pis and Sensors so that is not an issue. The Half-Pint Runt Rover Kit comes with 4 x 140RPM prewire motors.