How to block porn sites

Hi all. I just fixed my sisters computer (which I've had for 5 days now) and I need some help before I give her computer back to her. My sisters computer was hit with a virus and I finally got everything removed but before I give her computer back to her I need help or some info on how to block or configure her computer to restrict access to porn sites so I am not spending 5 days fixing this again for her. I've done a lot of research and I've come up with nothing. Any help would be greatful and greatly appreciated. Thank You!!!

 

Look at these apps:
http://www.topshareware.com/Parental-Filter-download-11816.htm
http://www.downloadjunction.com/product/software/116280/index.html

 

IE has a content filter built in. If she uses Internet Explorer just use that and enter a password only you know. It is found under tools, internet options, content. Just click on the enable button on the content adviser. Not sure how well this works, because I have never had to use it myself. I know that I have worked on systems that have and you pretty much can't browse to sites anywhere that may be suspicious without the password. You might want to test it out before you give it back to see what it blocks. hope this helps.