Is there a way to block web pages in FireFox without third party software, or the c:/windows/system32/drivers/etc/hosts method. Or if there is a way I can make someone need to use a password to access FireFox.

You listed the 2 easy ways.

There is another method but... much harder.

Get the source code for FireFox. Search for the place where the addresses are processed, and hack the code to block what you want.

Ok now method #4. Easier but might not work good. Define wrong routes to the hosts you want blocked. Use ROUTE commands to define these routes, and put them in a startup script. However the problem is to be sure that the route is set up, the system may reset them on startup or upon connection to the network... And also the user may see it and remove your phony routes...

I suggest strongly method #1 (3rd party software). For example you can use your firewall (you DO have one, don't you ?), I mean not the useless Windows XP "firewall" but some real stuff such as Kerio. It is easy to write a rule to block selected IP addresses, or address ranges. You can protect Kerio's rules with a password.

I'm not sure I understand what you mean? To block websites w/out 3rd party software, you could use a proxy server or firewall I suppose.

If you mean, block OTHER people from accessing a website using firefox (as in, you own the website and you want to restrict firefox users) you could look at the UserAgent header.