The problem with monitoring software (of any type) is it can be bypassed.
When my son was old enough to use the household computer online I put in the main room so I can monitor your his activity online myself and talked to him about not sharing personal information with anyone he didn't don't know in person.
I also told him to switch off the monitor if they see anything onscreen that made him feel uncomfortable and to tell me so that I could sort it out.
you could also goto www.takethislollipop.com
to errm make the point (warning not for the faint of heart) it put the heaby jeebies up me and i'm in my fourties