At my house I allow my son (11) and daughter (9) to have computers in their room with Internet access. The only reason I do this is because I have locked down their computers with some type of "Nannyware" over the years. The problem with most of these types of software is that is slows the computer down significantly and is obtrusive while the kids are on the Internet.
Last year I tried the OneCare Family Safety program and thought it was ok (with a bonus of being free). I had to create LiveID accounts for each of my kids and they had to login to LiveID to access the Internet. It worked, but was a little painful. On one of the computers (the one in my son's room) the software would randomly disable which was pretty scary.
This last weekend I decided to rebuild the computers and realized there was a newer version of program available on Live. It installed cleanly and they have integrated the accounts with Windows accounts and provided an option to automatically login to the LiveID account. Additionally, the performance is much better than it was before so the kids login to their Windows accounts and are off and running. They know the software is there and get blocked from certain sites, but it is unobtrusive and sits silently in the background.
Furthermore, the online reporting is drastically improved. I can quickly scan my kid's Internet activities and add or block specific sites even from the office. If they run across a site that is blocked they can automatically ask for permission and an e-mail is sent to me immediately.
Overall, I would say this version of the program is a home run and I feel much more comfortable about my kids being protected during their online experience. I highly recommend this software for your computers if you have kids.