Install the msblast.exe worm?
You could probably install WinVNC and connect to it remotely (assuming firewalls are non-existant or set up correctly). WinVNC allows you to remotely control your computer from your desktop. You could set it up to shutdown (although you'll have no guarentee (sp?) of success as part of shutting down includes killing the WinVNC server and closing the internet connection). If you're 99% that your machine would shut down by itself without you intervening (for whatever reason), go for WinVNC.
http://www.realvnc.org/
Good luck!