You could purchase software to track and prevent access to offensive
on-line content. However, I found that a combination of free
services tends to do the trick. The basic version of
Open DNS allows you
to block offensive sites by changing your default Domain Naming Service.
Enabling 'Content Advisor' in Internet Explorer adds another level of
protection. IE8 also contains parental controls, useful for
non-Administrative accounts (the kids aren't using administrative rights,
are they?) Finally, restrict the search engines to one and set its
parental controls. Google provides parental search parameters, other
providers may also.