METHOD # 1
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 , 60secs*60mins=3600secs.
Make up a name for the shortcut and you're done.You can change the icon by right clicking=>properities=>change icon=>browse
TO ABORT:To make an abort key to stop the shutdown timer just create another shortcut and makethe "location of the shortcut" to " shutdown -a" without the quotes.
METHOD # 2
Here is another trick to shutdown at a specific time, for example you wish to shutdown at 11:35am. Type this instart=>RunType Code: at 11:35 shutdown -sTO ABORT:Code: shutdown -a