If you ever had the need to automatically reboot your system (whether it's a workstation or a server), knows that this is not a very simple thing to do. The shutdown command of Windows is often limited (e.g. it can't be used when nobody is logged on, or when the system is locked), and other applications are often too complex, or not free, or may even contain spyware and other ill-made wares. Windows Sysinternals has a solution.
The application is called PsShutdown, and is downloadable for free:http://www.microsoft.com/technet/sysinternals/utilities/psshutdown.mspx
PsShutdown is quite similar to "regular" shutdown - the former accepts the same parameters as the latter, but has various additional features, such as logging off users, locking the work station, and foremost: shutdown of the system when nobody's logged in, or when the console is locked.
Suppose you need to reboot your system once a week. You would then create a Scheduled task (using the built-in Windows task scheduler), set to be executed once a week (or whenever you need the system to reboot), using a privileged account (i.e. an account which is capable of doing the system reboot), and run this command:
psshutdown -f -r -m "automated planned reboot" -e p:0:0
Note that the best practice is to put the commandline above in a .cmd file, and have that executed by the scheduled task.