Do you know that you can make your PC shutdown at a time u wish to? Here is the trick!
Right click on your desktop and choose "New -> shortcuts".
In the box that says "Type the location of the shortcut",
type in "shutdown -s -t 3600" without the quotation marks and click next.
Note: 3600 are the amount of seconds before your computer shuts down. So, 60 secs * 60 mins = 3600 secs.
Make up a name for the shortcut and you're done.
You can change the icon by right clicking->properties change icon->browse.
To make an abort key to stop the shutdown timer just create another shortcut and make the "location of the shortcut" to " shutdown -a" without the quotes.
But if you want to shutdown your PC at a specific time,for example you wish to shutdown at 11:35am? Go to Start and then run. Now type this:
at 11:35 shutdown -s
and if you want to abort type in Start->Run again: