keyloggers arent bad, zonealarm will filter webcontent, but with the information you gave, a good answer isnt possible, if the "child" is 14 or so, you had best let them know they are being monitored, as its a huge breach of trust, apps will never take the place of a good human relationship and god forbid they find out you are monitoring without their knowledge

so waht do you want to do?? log their activities, filter content?? put a time limit on them??