I'm new here, I assume Turtle's got his power button figured out OK.
If you go to (for Windows XP):
>>Power Option (Click this)
>>>>Power Buttons (drop down menu): This lets you set what the power button does. One of the options is "do nothing," so if the power button causes problems, that might be worth using as a setting (esp. if friends or family share the computer and don't realize using the power button to shut down causes problems).
Just posting this for my own reminder, cause it was news to me.