Networking, borrowing files on home computers

I hope this is where this should go.

I have two Windows XP computers on a home network, both are the Home Edition, the network was set up for sharing an internet connection, I have decided to star sharing files and would like to be able to check what my daughter goes to on the net without getting on her computer. When I first started sharing files there was no problem, but then got to where when I tried to get anything off hers I did not have permission and needed to check with the admin. the last time I tried to get stuff off mine to hers it said the same thing. Is there a way to fix this?

thanks