Anyone know of a GOOD way to give limited Internet access to a user?

I've been asked to configure Windows 7 Professional computers to limit access to only a few select programs. I've had good success using a standard user account and setting options in Group Policy (e.g. "Only run specified Windows applications").

However, I've also been asked to enable limited Internet access - i.e. access to only a few select websites. I've been able to do this to some extent via Content Advisor and a "fake rating", but one of the sites I need to allow calls on several other websites, such as Facebook (e.g. the "Like this" button), so in order to stop Content Advisor from prompting for a password every time the user clicks a link on the page, I have to enable the whole Facebook domain, which defeats the point of limiting access in the first place!

Does anyone know of a program/method of limiting Internet access that is smart enough to realize that a website is calling on another one (often with impossible-to-allow random urls, such as Internet ordering features) and thus allow it through?

Any other solutions/suggestions would also be greatly appreciated.

Thanks for your help.

How to Block an IP Address on a Computer | eHow.com
How to Restrict Web Browsing Using Internet Explorer - wikiHow
Restricting Specific Web Sites in Internet Explorer Using Group Policy
Internet censorship - Wikipedia, the free encyclopedia

Above may give you some ideas.
Have you got a firewall that monitors traffic?
Can you block IP ranges with your firewall?

Thanks for the links, but I've already tried using Content Advisor. As I understand it IP blocking, like Content Advisor, will only block certain websites. I don't want to merely block certain sites, I want to allow only a specific, limited list of sites.

The firewall has Internet filtering available, but it's a yearly subscription that isn't suitable for our needs.