Is it possible to use Windows Firewall to block specific web sites for all browsers?
This is a very generalized question... (more information would be useful...) as the Windows Firewall exists in different versions... and has different capabilities with each version... etc.
(Assuming you're running windows 7, and you're ONLY wanting to use the windows-firewall) The short answer is: Sort-of. You can deny access to a IP address, which would in-turn deny access to any websites hosted on that IP address. This rule would apply to any application attempting to connect to that ip-address. (Windows 7 has the only windows-firewall that blocks outbound connections) The only fly in that ointment, is that most companies of any large scale have many IP addresses all of which serve pages for that website. yes you can block them all, but it's really an excessive amount of work.
(If you don't mind getting your hands dirty) you can also modify the hosts file (c:\windows\system32\drivers\etc\hosts) and put a bogus entry in there for the domain in question, but a lot of anti-virus with some level of heuristics will identify this as some sort of suspicious activity, and others will silently wipe out any changes you make.
The third option is to invest in a router that has some sort of content-filtering options... (there's quite a few out there that work quite well that aren't too expensive) or look at software like netnanny or other solutions like OpenDNS to provide whatever level of filtering you require.
Possibly, depending on which version of Windows you're using, although I don't recall ever seeing any such options.
It's probably easier to just add entries into your C:/WINDOWS/SYSTEM32/DRIVERS/ETC/HOSTS file (it's a plain ASCII text file that you can edit directly with Windows Notepad), like so:
The IP address "127.0.0.1" is localhost (your local computer), and using it for the web site addresses (the domain names) you wish to block will result in a timeout (assuming you're not running a local web server like Apache HTTPd; if you are, then its web page will appear which will be fine anyway).
Make sure that you block both with and without the "www" portion; this is quite easy as you can specify multiple sites on a single line by delimiting them with spaces, like so:
127.0.0.1 www.bad-web-site.example.com bad-web-site.example.com
Maybe you can try Parental Control? The Windows built in or anything third party...