Safe Guarding the Family PC: Looking for Internet Filtering Software

[Stoney]

I am looking for a software that will work in the background and filter content from young eyes using the internet. I tried the options in Windows but it is so intrusive that it blocks any time someone wants to use google or their favorite sites. I am not trying to stop internet use but adult content.

What do you recommend that can block certain content according to my needs/directions in stealth mode? Any good free ones out there?

Thanks.