If you mean set a password so a person cannot get to the interent, then I think the answer is NO.
If the PC can get to the internet, and the user has access to the computer, then there is always a way of doing it (download a different browser for example).
Of course you could always pull the cable out, but that is a bit drastic, and easy to get round anyway.
you can get a desktop lock that will stop any browsing of the internet, password protected ,also you could set a password in bios that will stop the pc from booting up .both pretty reliable but the bios one is free.hope this help's