You can disable it from the guest account or limited user:

1. go to control pannel and then admin tools. chose local security policy.
2. click on software restriction policy and then on the top menu chose action and create new (if there is one yet).
3. click security levels and then right click disallowed and then make default and click yes to the message.
4. double click enforcment and chose all saoftware files and all users except admins. under additional rules create a new path rule from action menu. there browse for the internet icon that is in the guest account. the path should be something similar to: C:\Program Files\Internet Explorer\iexplore.exe then security to disallow.

Thats it! try to use the internet now from your account and then from the guest account. You will be able to use it but guest wont! Heheheh enjoy….