I am showing a PowerPoint Presentation using two monitors. One for the presenter and a large monitor for the audience. How can I get what is on the audience monitor to share with other computers on our LAN, in real time without using the internet?

MyVision has software for teachers for managing there students using computers. It has many features that I will not need. I have a trial version that I am testing. If you know of any other solutions for my task I would like to test them also.