Remote Viewing & Control of Networked PCs

So today i was introduced to some software called PC Duo. You install a control console on one (or more machines) and a client on each machine on the network and it will allow you to do several things.
You can view what is happening on any machine without the children having to know. You can also take control of a computer to demonstrate something, or fix it without going around school and still having access to your own desktop; along with other more common features such as messaging a single, or multiple desktops, and having chat sessions with a machine MSN style.
While not a teaching based program there are useful features such as screen blanking, mouse and keyboard suspension. Both of which would be very useful in an ICT suite.
We currently have a 30 trial version so will be testing these features across 5 machines to see if they are as good as the sound, and work as expected. And most importantly if they justify the significant cost!