Security Problem

I have Windows XP for my OS, and I share my computer with the whole family. My 14 year old step-son is one of the users. I didn't start getting viruses until he started using the computer. I understand a lot of viruses enter via porn sites. He has chosen to protect his files so no one can open them to see where he has been.
Is there any way I can open his files as administrator to monitor where and what he has been doing. Perhaps any software that might give me his passcode or a keylogger of somekind. I do not want to go to jail for something he may have been looking at.
I know I could boot him off, but I hate to resort to strongarm tactics until I have proof.
Thanks

 

There are dozens of ways to skin this cat, Ill throw a few at you.
Software called Net Nanny. Google it for there are too many details to include in this response.
If you log on as an admin. You should have explicit rights to any and all files and folders on that machine.
If you have his log on which you should, check his browser history and temp files.
If you do not have his log on you can go strait to the folders where they are at and check them. IE will save all .gif's for easy viewing.
Even if he deletes all browser history, cookies and temp files, the index.dat file will still hold the websites he has been (little known fact that M$ does not reveil)
As an admin you can change his pass. even if you do not know it and give him the new one.
If you have a SOHO router with a decent logging tool you can use SNMP to write a log of every and all websites that get visited.
There are more forensic type tools out there and quite a few Cracking programs but I do not think you need those just to do what you want to do.
Good luck