When I first moved to Windows 7, I accidentally hit " Sleep" button that I supposed to be "Shutdown".
Anyway, you can change this button to any what you like such as "Switch Users", "Log off", "Lock", "Restart", "Shutdown" or "Hibernate".
This is the tip on how to change the "Power" button,
- Hit "Start" Orb
- Right-click on the power button, and in my case "Sleep"
- Click on "Properties"
- Then, click on "Power button action:"
- Choose the way you want this button to behave and in this case I choose "Shutdown"
- Finally, hit "OK"