Vista - Parental Controls blocking more than they're supposed to

I set up my parental controls to block only porn, but now as I surf around trying to test it out I find that a lot of sites I didn't want to block are being blocked (eg. sites about internet filters and media websites). Is there any way to make the filter actually ONLY filter those categories I actually want? I can't keep entering an admin password every five minutes.

Also, is there any way to make a happy medium between "Keep Blocking" and "Always Allow"? I'd really like the option to say "Allow once" - not only does this allow the ability to judge whether a website should be allowed or not, but it also means that if you want to block something you've once allowed, you don't have to go hunting for it in the allow list.