This is little bit of windows hacking when you say you want to shutdown a remote computer on your LAN network, if you are doing it for FUN then its ok.
But let me tell you, this may also cause some potential data loss at the remote computer.
Requirement: You must have administrator rights in order to remotely shutdown a computer.
1. Start>>Run and type cmd and press Enter.
2. type shutdown /i
3. add the computers on your network ,set the display timing and enter the shutdown comment.
Note: You can know what more you can do with shutdown command by typing shutdown help | more and the command window.