An anonymous reader asks: "My SO just inherited a computer lab from a departed teacher who was no security guru. These are Windows XP systems, and security basically consists of a password on the admin account, a subscription to McAfee Security Center, and a free Internet filter. The students have access through a non-passworded 'limited' user account that doesn't seem to limit much. They have been going in and changing settings, downloading games and music, and generally screwing the computers up during class time, in many cases leaving them unusable. As the geek in our house, she has asked me to give her a hand, but while I have dealt with some security issues in the past, it was to protect against remote intruders, not against someone who has to have access to the keyboard. Any suggestions on the best way to lock these systems down?"