Ubuntu :: Easy Web Filtering - DNS Settings Don't Appear To 'stick' Once The Netbook

I've been trying without success for the past couple of weeks to setup a filtering system for my little sister's netbook. The main problem I've been running into is inconsistency. First, I tried using dyndns per the instructions here: [URL] The problem with this is the DNS settings (and in turn the filtering settings) dont appear to 'stick' once the Netbook touches a different network. So if I sign onto a different wireless network than the one I used to set up the filtering, it stops working. The reason why is Ubuntu will overwrite the current DNS settings with those of the new network (I have no idea why, and am too frustrated to figure out).

Also, I noticed that even if the settings did stick, they're fairly easy to disable because all she has to do is stumble across the DNS settings, change them back and voila. I've had great success with OpenDNS on Windows boxes, but there doesn't seem a to be a feasible way to apply it to Ubuntu. Dansguardian looks like it may be worth a shot, but I've seen dozens of "simple" configuration guides, none of which that actually looked simple. So my question is this, what is the easiest, most bulletproof way to setup web filtering 10.4? Preferably something that a 12 year-old could easier find her way around.