Youngsters, teenagers and safety. Parents, do yourselves a favour. Do not allow use of a computer by them in private places. Best place to put a desktop computer that they are to use is in the kitchen or living room. Notebook PCs for them is particularly risky. The Internet is a wonderful and beautiful place, but it carries risks. Youngsters and teenagers are not necessarily equipped to judge the dangers. They can get themselves into a lot of trouble. Supervise Internet use.
I would advise strongly against allowing passwords on these computers.