I want my windows XP to shut down automatically with in specified time as soon as i switched on my system

You can't turn off your PC within a specified time but you can Hibernate it.Hibernation is very similar to Shut Down but it saves what ever you are doing.To do so:1) Go to 'Control Panel'.2) Select 'Power Options'.3) Click the first tab in the new window.4) In the last scroll-box select the time you want and then click OK.Hope this helps!-MIFRAS