It looks like you can't unless you give them admin status in Win XP home, which Media Center is based on.http://www.microsoft.com/technet/community...ty/wxp0402.mspx
Excerpt from Microsoft page:
Q: dhopton_MVP : It's annoying - I have a friend who wanted to stop his brother from messing with his documents, but let him play games. He came up against the same problem as you.
A: The "make private" thing would help this as well. It prevents other admins from seeing documents (they can still take ownership)
Q: dhopton_MVP : Tim: Because the permissions required are the same as an administrator. For example certain registry keys have permissions that only allow the administrators to create/edit them, and games use these - there isn't really much of a way round
A: Tim: We do have this concept in PRO (it's called the Power User) but our usability studies for Personal showed conclusively that Home users did not want to deal with more than two groups
Q: Rebecca : Are you saying that if I give my son administrator privileges that he could take ownership of my documents?
A: Yes, if you know how. There are now no visible tools to do this out of the box other than safe mode boot
Q: Rebecca : Is this only in NTFS?
A: FAT is even worse, it has no security
Q: Rebecca : So what do I do to keep all the important stuff private and still allow him to play games and things?
A: Encrypted File System is available on XP Professional (not on Home).
You can try installing the games on each of their accounts separately temporarily giving them admin status and then changing it back to limited user. I don't know if that will work or not. If it did, you would think the Microsoft engineers would have suggested it. I don't know if Media Center would work with XP Pro even if you wanted to "upgrade", and I sure wouldn't let kids run loose with admin accounts.