How can I restrict the Local Admins from accessing a specific folder ?

Dear All
I have an application which collects some data on a specific folder on drive C. The operator of this App must be a member of local admins (windows XP), the app will not run otherwise. I want to prevent the operator from modifying the contents of this folder and just let him write to this folder via app and make him unable to change the contents of the files, out of app’s order. Have you ever experienced such a situation?