You can rely on Z-Cron
as a robust scheduler that can handle not only shutting down the
computer, but also launching programs, leave reminder notes, and
cleaning directories. Similar to the Unix Cron scheduler, and far more
powerful than the native Windows task scheduler, Z-Cron is an
aggressive sergeant at arms, able to tell your computer what to do and
when to do it, leaving you to get on with your life when you're away
from your machine. Besides tasks, Z-Cron also has the capability to
schedule tasks to run daily, weekly, monthly, once, and regularly at
your system start-up.
More information at Download.com