restricting my kid's access as a user

My little 2y kid, while using my computer to play games, delete my stuff and mess alot around, connecting to dialup ISPs and other things.

I want to restrict his access to only his games and nothing else. For that I made him a limited user, without a password, and done my self a password, as administrator (I use XP pro)
But he still has access to every thing!
He can access 'My documents' and delete anything there. When I right-click my documents > sharing and security, to make it private, the option is not active. Why?

And, is there a way I can restrict his access? like hiding start button and systray, without hiding them for me as an admin?

Where can I read about restricting a child's access in Windows XP?

 

1 Click Start and select Run
2. Type gpedit.msc in the text box and click on OK.
3. The group policy editor will load. Navigate through the folders and you will discover hundreds of items that you can limit access to and control*

*Note: This only works in XP Pro.