You can actually shut down Windows XP without a click, but first you have to get set up.

1. Go to your Control Panel and choose Power Options.
2. Select the Advanced tab.
3. Under "Power buttons" you can choose what happens when you press the power button on your computer. It's probably already set to shut down, but it's a good idea to make sure before you start wantonly shutting down your machine.
4. If it's not set to shut down, choose that item from the drop-down list.
5. Now you're ready to shut your computer off. Just hit the power button. Don't touch the keyboard, and keep your hands off that mouse. It's perfectly safe to shut down your computer with the touch of a button. Enjoy!

Source: TechTV