The default action for vista power button is to put your computer to sleep. I found this to be infurating while working on my laptop. instead of shutting down like i would expect it to my laptop would go in to sleep mode and slowly dran the battiers till it was dead.
After a little Google searching I found this article to change the default action for the power button in vista. (with pictures)
- Go to Control Panel.
- Click on System and Maintenance link.
- Click on Power Options applet.
- Click on Change plan settings on the power plan that is been used or activated.
- Then click on Change advanced power settings link.
- Expand Power buttons and lid options tree.
- Expand Start menu power button option.
- In the " Setting" drop down list, change to Shut down. If you prefer to hibernate your system, choose Hibernate, or Sleep if you want to revert back to out-of-the-box default. Vista Start Menu Power Button Setting
- Click on OK button. The change will take effect immediately, and you can now shutdown computer properly by single clicking on power button at Start Menu.