Create a desktop shortcut then right click/properties & asign it some keys.
To create a shutdown shortcut on the desktop:
1. Right click on an open area of the desktop
2. Select New / Shortcut
3. Enter in "shutdown -s -t 00" - no quotes
4. Press the Next button
5. For the name, enter in anything you like. Click on the Finish button.
If you have a keyboard with extra buttons, you can configure these keys from control panel - keyboard. I know for sure that MS Intellitype has the shutdown option in the list when you click 'configure' (or whatever is the exact term in English), should be similar for Logitech or other manufacturers.
Or follow the advice in the previous posts. Actually many different ways to do it.