I believe you'll need to take ownership of the files in order to do anything to them.
As Newby has already said, you'll need to disable simple file permissions, which is accessable from the "Folder Options" menu in My Computer -> Tools.
After this is done, you'll need to make sure you're logged onto the administrator account. right click on the directory you want to change, go to properties and click on the "Security" tab. Then click on the "Advanced" button toward the bottom of the window. Click on the "Owner" tab, select your account on the local machine, check the "Replace owner on subcontainers and objects" checkbox and click "Apply." This may take a while to complete.
After it's finished, click on the "Permissions" tab, click on the "Add" button, add your local account to the list, uncheck the first box ("Inherit from parent the permission entires that apply to child objects. Include these with entries explicity defined here.") and check the second box ("Replace permission entries on all child objects with entires shown here that apply to child objects."). Again click "Apply." It could take a while, but once it's done, you should have access!
I think I wrote a word document (complete with screenshots) on this very subject for a kid at school who had a similar problem. I'll see if I can dig it up.
