Blocking usb devices for students

[Neville]

What is the best way to block students from bringing usb devices and plugging them into the computers, but we would also like to be able to switch the computers on and off ie if a student has to save work we can allow open up the usb port let him save his work and then block the port once he is finished. Does anybody know of any good software that can deal with this, also where can set up in the GPO for students not to be able use the usb ports for the time being untill we find a suitable solution or software.

[SpuffMonkey]

I believe the latest version of AB Tutor allows this as well as all the other great stuff.