Well, it's a Windows XP machine, so no built-in filtering system. The problem with OpenDNS is that the little girl's computer is on a network with her parents' computers - and I don't want to restrict their access.

I really think what I need is a software solution on the local machine. I've heard of NetNanny and others, but I'm not sure how helpful they are - and I don't want something that is going to give a ton of false-positives - I want her to be able to have as much access as possible without coming across porn and the like...

I'll research through the weekend and post back what I decide to go with. More suggestions are welcome of course.