Something to consider... (Score 1)

You should consider disabling things such as the command shell ("cmd" through the run menu) directly through the registry. While you're at it, find some decent software to track where your students are surfing, and block websites accordingly. Some decent web-filters allow you block sites on the basis of Given keywords. In addition to this, see if you can get funding for software called "Vision." Essentially, it allows you to control/stop any computer user's activites... and gives you constant watch over the systems. Hopefully that gives you a place to start.