my local robotics club did a project like this a while ago, all of the bots were areduino baed adn used 2 360 modded servos, they onlyever got to the stage of bumping into things and just avoiding walls but you could do so much more with a few xbee modules. The bots are called box bots and are all laser cut out of acrylic. http://www.botbuilder.co.uk/store/index ... ucts_id=57 The guy that makes em is called steve by the way.

The arduinoes need to be programmed in C++, im not sure how happy you are with programming but if youve never done it before there is tons and tons of stuff on the internet.

hope this helps and good luck with your project