Just install [link=http://www.mozilla.com/firefox/]firefox[/link] and couple of [link=http://www.hardwareforums.com/firefox-extensions-tweaks-11470/]extensions[/link] with it.
By the way, there are couple more things which you can do with computer and Internet explorer as well.
Set a admin password for your computer and a guest account.
in the internet explorer, set the security level you want from Internet Explorer> tools > internet options > security tab. If you have some sites which you know and you dont want somebody to see that then put them in restrictions.
Hope it will work for you.