Of our five childen, only Rachel and Jacob know how to use IE without assistance. We have shortcuts for their favorite websites displayed to make it easier for them. Being 7, Jacob is only interested in games so no worries there.
Rachel is 9 and has learned how to use Google to search for information. When she develops an interest (her latest was learning how to speak Japanese) she will do a Google search. She has also used it for reports for school. I have a good enough relationship with Rachel that she feels comfortable talking to me and asking questions so that if she did happen across something inappropriate I am confident she would come see me. I know that will most likely change at she gets older, but for now it works.
Right now we don't feel the need to install any parental controls on the kid's computer. Given what they use it for it just doesn't seem necessary. That said, Cary has blocked a few of the websites the kids were frequenting because they were busy playing games when they were supposed to be doing other things.. you know, like homework... :)
As the kids get older, who knows
. I haven't really thought that far ahead.