Contolling access to the Internet

Whet is a good way to control access to the internet?

Windows 2000 server, clients machine are 2000/xp the default getway is pionting to the router.

what can I jdo to control the the access to the internet?

any good software? or any idea.
I am at the moment learning how to set ISA but I would love to use a non microsoft software.

Thanks

 

What kind of access do you want to control?

 

Hi,

I wish to try and prevent access on diff' levels.

CEO can go where ever he wish
other machines should only go to certain websites


Thanks