Lock, Log Off, Restart, Shut Down Windows in One Click by Brutus

Brutus is a freeware software that lets you lock, log off, restart, or shut down Windows with a single click!

Brutus lets you log off, restart, or shut down a computer running Windows 98 Second Edition, Windows Me, Windows 2000, Windows XP, or Windows Server 2003. In Windows 2000, Windows XP, and Windows Server 2003, you can also lock your computer with a single click.

Remember, Brutus is freeware and provided as is, without warranties of any kind. So if you decide to use it, you are responsible yourself for any consequences like computer crashes / losses should they arise with it usage. But that is true for most software.