Monitoring his computer time and his usage was one of the things my difficult child fought hardest about when he lived here. The SCHOOL let him post personal info on various places ("If the filter lets it through it must be OK" my behindy!).
The funny thing is that he had more access here than he does at my parents. They have him fully locked out of most things. Of course, he still goes to the University and uses their computers, but we keep finding and erasing his pages. He prefers zanga.com (or is it xanga.com?) never sure until I go check it. Right now he is only posting the sterotypical teenage no-one understands me, I am so deeeep crud. But once in a while it gets to be too much.
Good Luck with this!