Parental controls aren't built into browsers. They are add on packages that sit between the browser and the big bad world. There are free ones about but teh best is simple, free and fun. Sit with your kids whilst they are on the net! Or if you are prepared to give them some freedom warn them that you will be checking logs as to where they have been(make sure you enable logging on MSN Messenger. If the logs are cleared you will withdraw PC access for a month.
If you have a network you could run a proxy on your main PC(i.e. not the kids one) and make their connection through your proxy. Even if they clear their logs you will still have a full set
