I recently discovered Peanut Butter PC Software, a children's browser. Basically, you set up your child's "backyard" so that only computer programs or websites you manually input can be accessed. Nifty! And all of their "choices" are in plain view in the Backyard, making it very simple for them to navigate. I like it because if they have earned a reward and I want to allow them some time on Disney Jr. for example, I can easily turn it on and then off again when they're finished. I just don't want them to spend all of their time on that sort of thing. I prefer that the computer be set up with mostly educational options and lately it seems they are getting older and starting to stray more from that. My son has grown exceptionally good at googling and apparently can spell "angry birds" without issue.

My husband and I go back and forth about the level of access the kids should have to the computer. Hubby is a geek by trade and wants the kids to learn on the "real thing" and he thinks "net nannies" will cripple their skills overall. I get that, but I think options both within moderation is a better choice. Peanut Butter PC is a good solution because I can turn the program on and off at will.
This review linked below says that kids can find their way out of it but I don't see this as a steel box, more like encouragement. Yes it supposed to do what it advertises, but if they figure it out my hubby will probably just applaud their ingenuity and we'll move on. Ideally, I want to corral them to learning programs and educational websites a little bit longer while they're young. There are times I don't monitor them as closely as I probably should on the computer, and this is perfect for those times (Like when I am doing individual lessons or piano time with one and need the other kid occupied but not rotting their brain.) As they get older, they are going to learn more about being responsible users of the computer but for now this is a pretty simple solution. Just sharing it here in case it helps your family, too!
http://www.peanutbuttersoftware.com/http://www.pcmag.com/slideshow_viewer/0,3253,l=228903&a=228816&po=0,00.asphttp://www.techrepublic.com/blog/window-on-windows/peanut-butter-pc-trying-to-keep-kids-safe/6428 ETA: I could not get it to work when I first downloaded and was very frustrated. It turns out it must run on an admin account so I could not use it on the account I specifically created for the kids. I put it on an admin account and it works fine now.