How do I track which websites other people are visiting on my computer after they clear the Internet history?

My boyfriend keeps staying up until 3am using my computer and he won't tell me why. It really bugs me and I want to know what he's doing without busting him the traditional way. Does anyone know of a way I can check what websites he is viewing even though he always clears the internet history?How do I track which websites other people are visiting on my computer after they clear the Internet history?
Try reading this,and see if it will help.


http://answers.google.com/answers/threadview/id/470387.html