Restrict Access

I am trying to set up a Limited user account for my grandchildren. I want to restrict access to basically everything pretaining to the operating system. I do not want them to be able to access the control panel, hard drive, regedit, internet options, run cmd etc. as I have set up content advisor to block the ever so popular sites such as myspace. I know that even with content advisor password protected, having access to the OS they can make changes to get around the security that I have set.
But I do not want to restrict my own access by using registry hacks that disable these features to me.
I tried a program called Folder Guard and followed the instructions to the "t" then signed onto the grandkids user account and they still had access to everything although I set up Folder Guard to deny access. Went back into my account and checked Folder Guard settings and they were still set as I had said. Restarted my computer 3 times and it still held my settings but did not block the user from accessing the OS.
How can I or what program can I use to restrict access to these operating files without locking myself out? This is a very serious problem as my 12 year grand daughter, even after having a very long discussion with her regarding the dangers of posting on these sites, has seriously compromised her safety.
I do monitor them anytime they are on the computer, but evidently the last time she was here she got on when I was asleep and she is also accessing these sites from home and yes her parents have talked to her about this also. They monitor them when they are on the computer and check history regularly to see what their children are doing on the internet, which she evidently does not know to clean the history yet, but that won't take long for her to figure that out.
Content Advisor even with password protection can be changed from regedit, other commands or even from the C drive. I want to block access to everything except the internet, their documents, IM, and programs that they need to use. Basically I want to have a limited user account with NO OS priviledges.
Any suggestions

 

If you are using XP, and set up a Limited User account, they already cannot do anything to the operating system.They can look, that is all they can do. They cannot delete, rename, move, or make any changes to the windows folder or any folder connected to it.
A Limited cannot make system wide changes. This means if it does not only apply to them, they cannot do it. Their startup programs can be different from yours.
This type of account has it's own registry, meaning things done to restrict you does not mean they are restricted. You have to log onto that account for those changes to be done with Folder Guard. There are some programs that can do this without logging on to that account, but none free comes to mind.
Then you run across the problem that Folder Guard can't do anything because it is running on a Limited Account. The solution for that is simple, first change the Limited Account to an Administrative Rights account, then log on to that user, and make the changes. Log off, and change back to a Limited. Everything you have done will stay done.
To restrict someone from getting to a website, why not just put it into the HOSTS file, located in C:\Windows\System32\Drivers\Etc. Here is an example of how to do this.

127.0.0.1 www.myspace.com
127.0.0.1 www.badwebsite.com

What this does is change where IE looks for the site. The way I have it up here, IE would look for the site at IP address 127.0.0.1, which happens to be your computer. Since the website is obviously not on your computer, they get a 'Page Not Found' error page. They never get there.
Since the HOSTS file is located under the Windows folder, it cannot be changed by a Limited Account, they can look is all.