JSI Tip 0015 - Shutdown button on the Welcome dialog box.

To display a shutdown button at Login, edit:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Value: ShutdownWithoutLogon REG_SZ 0 or 1

When this value is set to 1, you can select Shutdown from the Welcome dialog box. If the value is 0, the Shutdown button does not appear.