All in one!!!
If you wanted an all in one thing...go with the big guys. Great things come in small packages.
Look at the Microsoft stuff, big bloated and full of crap that most of us will not or will never use!
Now Linux on the other hand has thousands if not 100's of thousands of small very good utilities. All it takes is someone to unite a few of these together and get an awesome thing. Oh pardon me someone did ==> IPCOP <==. These geniuses offer their hard work to us for free. If you like what they have done then you can help these projects by $ or helping in documentation or whatever.
All it would take to get content filtering is download Dansgardian and most likely install in the same fashion as copfilter.
This is just my opinion.
K.