Have had this software running on the network for 2 years and have had no trouble with it what-so-ever, software updates are done automatically for you, and with each new version, a new feature is added which just enhances the functionality of the program. Join the forum as well, if you have any problems they are more than happy to help you.
Program is very easy to use, and is policy based, and can be locked down by yourself to stop teachers from messing settings.
The kids hate it because you can block sites, stop programs etc.
Might sound like i am giving it a sales pitch but i think it is a brilliant program