Aah., ::) The arena has bumps of 5cm diameter and a ramp of 40degrees inclination. You can view it here-
(http://www.techfest.org/img/competitions/hydra2.jpg)
There are zigzag obstacles, a ramp and the bumps at the top right corner. If you can spend a little more time you can see the details of the event over here - http://www.techfest.org/home/event/magneto (http://www.techfest.org/home/event/magneto). Select 'Arena' to view details about it.
Now the thing is that who finishes the track in the least time wins :D Simple. . . But to finish it quick we must have 'SPEED' and to overcome those obstacles we must have 'TORQUE'. . Initially i thought of using stepper motors and later found out its a very bad idea :-[ So, I can't figure it out which kind of motor is best . . but please don't suggest me some rocket stuff .. :P later none can see the robot once it starts ;D