How to Block All Websites Except One
You might want to block websites for school filtering, parental controls or any number of reasons. Web browsers have different built-in controls for website filtering, and security software such as Norton or McAfee have their own options. Blocking can be achieved in many different ways, but Windows Vista offers the most straightforward method for blocking all websites except one using its User Controls feature.
Open the "Start" menu. Open the "Control Panel," followed by "User Accounts" and then "Parental Controls."
Select a user account that does not have Administrative privileges, or create a new one by clicking "Create a new user account."
Click "Windows Vista Web Filter" under "Windows Settings."
Select "Block some websites or content," check the "Only allow websites which are on the allow list" box, and then click the "Edit the Allow and Block lists" link.
Enter the one website you want to allow in the "Website address" box and press "Allow."
Press 'OK" on each open window to enact the changes.