Internet Filters for Mac

Hi All...I was successful in getting my father to switch to a PowerBook, and now he got a new iBook G4 for my little bro (13 years old). I had an internet filter installed on the PC he used to use, but now that he's on the iBook 99.9% of the time, I need to find a new filter to make sure he doesn't wander off into the murky side of the internet. Any suggestions? I haven't been able to find ANY mac software that does the job.
Thanks for any help!

--DT

Thanks! This looks perfect for me. I will order a copy today.

--DT