I sometimes visit webpages that I do not want other people to see. So I regularly clean internet history (basic methods, in the tool bar, internet options delete internet history), but I wonder still my roommate who shares the computer can track the internet history. Is it possible to see the internet history if it is regularly cleaned up this way? I know there's a softwar out there that will take care of this, but can I do it by myself?

Just clearing Internet history isn't enough, you also need to delete temp internet files and cookies.
A good little program that does this and so much more is CCleaner.

Do you want to see what they can find, if you go to start and click on it, go to search or find and type in something like sex, and watch what comes up even if you have cleared you history. It is scary what the computer hold and a dummy like me can find out what has been looked at my it, si if they know what thet are doing they could have a blast with what you have been doing.