Users ought not keep files on their desktops. (It is okay for admins, as we understand the risks). If you are about to do an upgrade, or just want a reminder, then FilesOnDesktop_Agent.vbs is for you. This will pop up a window with a list of files and a dire warning about data loss. If you have XP with the Agent installed, then Merlin will appear to get their attention. Run it in the logon script or a startup script.