Create scheduled task to Shutdown Computer

Hello,
I have a simple task to be done when I finished downloading my favorite movies from Internet. The simple task that I mean is shutting down the computer. Yes, since I won't wait for my computer to finish the download. The download process requires an estimated time of 4 hours.
So, I would like to have my computer turned off after 5 hours from now. But how to do that? Is there any built in application for shutting down the computer?

