Set Your Computer to Shutdown at a Specified Time(Vista)

Learn how to set your computer to shutdown to a specified time.

Open Task Scheduler by going to Start , All Programs, Accessories, System Tools, and then open Task Scheduler.
Click Create basic task on the right side of the Task Scheduler.

Give the task a name and then click Next.

Select when you want to shutdown the computer and then click Next. The next screen will differ depending on when you want the computer to shutdown.

Next, choose the rest of the details about when you want to shutdown the computer and then click Next.Choose to Start a program and then click Next.
Type shutdown under d type –s –f –t 0 in the Add arguments box and then click Next.

Click Finish on the next screen to save this scheduled task.