Windows 7: screen saver/application running

I have to set up touch screen monitors at trade shows around the world. I have an application that runs on the desktop of win 7 and converts the apllications such as games, office and internet links into a series of large touchable sized icons. This application also removes from the touchable screen the power to exit the application without a keyboard which means that how I set them up ishow they stay, a great saving of time at a show. So far so good. What I would now like to do is;
If no one has touched the screen in a set period of time, I want to run a short application (such as a power point presentation) but when this finishes, revert back to the screen before it launched the application and then wait again for the time out. In this way when the screens are being used, all is well and when it is slow, the power point acts like a 3 min. actractor screen.
Does anyone know if this is posible in win 7 or know of any applications that will allow me to do this?
Kev