Si está utilizando Internet Explorer que puede bloquear sitios web específicos siguiendo los pasos:
1. Open Internet Explorer. In the Menubar click Tools → Internet Options → Content. In the Content Advisor box, click Enable.
2. Click the Approved Sites tab. Enter the address of the website.

Keep in mind - if you want to block the complete website put * in front. For example to block myspace completely, type *.myspace.com
Click Never and then OK.
3. Click on the General tab and make sure to select Users can see websites that have no ratings
4. Enter a password you can remember easily with a hint.
5. Click OK to safely surf the Internet.

O puede utilizar un software de filtro de Internet: http://www.cyclope-series.com/products/internet-filtering/filters.html