LanShutDown is a FREE program which lets you shutdown, restart, log off any computer on your network, but the primary requirement to perform these actions remotely is you need to have administrative privileges.
You can run this tool and shutdown any computer running windows 2000, XP or 2003. The program package includes two console programs with which you can use LanShutDown tool from command line also. With the command line version of this tool you can automate the shutdown and reboot of your computer