To hide the notification area (system tray) in Windows XP, perform the following steps:

1. Start the registry editor (e.g., regedit.exe).
2. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
   registry subkey to hide the notification area for the current user, or navigate to the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer
   registry subkey to hide the notification area for all users.
3. From the Edit menu, select New-DWORD Value.
4. Enter a name of NoTrayItemsDisplay, and press Enter.
5. Double-click the new value, set it to 1, and click OK.
6. Exit the registry editor.
7. Log off or restart the machine for the change to take effect.