A situation may arise that requires you to hide the system tray icons from the user, to do this:
This registry hack will hide all icons in the system tray.
Open up Notepad and copy the following:
Save the text file and rename it to for example "XP_HideTrayIcons.reg". Then merge it into the registry by double clicking it. Logoff (or end the explorer.exe process and restart it) and the user's tray icons will be hidden. To undo this, simply change the value to zero.