You can make IE go into kiosk mode through M$ IEAK kit or whatever it's called, which removes the address bar, but once you have a search engine on the browser, it'll be virtually impossible to restrict the user from navigating to another website.
I'm not sure if those cybernanny softwares can help in restricting to only one site - never tried.
if you have mcafee internet security you can use Privacy expert and make ti where you can only browse one site .. There is also the way below:
add the website you want allowed to your HOSTS file, then manually configure the connection, and put 0.0.0.0 for the address of the DNS server..
result: the computer will only be able to resolve the address of that one website..