Microsoft have released the full version of their Robotics Developer Studio 4. It is built to incorporate the Microsoft Kinect sensor easily into robotic development.
The robot recommended to go with the setup is available from Parralax.com for around £785 (which does not include the Kinect sensor), but luckily this isn’t essential to use the software as a Microsoft have also built in a simulation robot.
It may be a little too technical for most secondary schools, but for a free piece of software there can be no complaints. Certainly worth downloading and trying out in a robotics club if you have one.