Thw Win32 API on NT supports remote shutdown. The NT Resource Kit has a tool called SHUTGUI.EXE for doing exactly that.
 
You can even find the source for such a tool in the MSDN Knowledgebase.
 
There are probably several such tools on www.winfiles.com. If not, drop me a line, and I'll dig out some of my old source code...
 
 
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SuperMicro P6DBS (dual UW-SCSI) BIOS 2.2, 2*Celery 300a @ 450Mhz, 384MB PC100 RAM
SCSI-A=4.3Gb+9Gb, SCSI-B=Tosh32x CD-ROM, Yamaha4416 CD-RW, Iomega ZIP100, IDE1=4.3Gb
IBM EtherJet 10/100 NIC PCI + Nortel ADSL "modem"
CL TNT1 AGP + Quantum3D Voodoo2 SLI PCI
SoundBlaster Live PCI (not Value)
Win2K build 2195 Retail (no 120-day eval)

or try remotely anywhere, awesome progie to admin your pc via a java enabled web browser
http://www.remotelyanywhere.com

Actually you can do it right from the MMC (Microsoft Mangement Console) assuming that the computer you want to reboot is running Win2K and that you have administrative rights on it.
 
Open up the MMC (go to Start->Programs->Administrative Tools->Computer Managment)
Click on "Computer Management (Local)"
Select Action->"Connect to Another Computer..."
Find the computer that you want to connect to (it must be accesible through file sharing).
Then once you have connected to the other comp and are managing it, right click on "Computer Management" and select "Properties" and then in the Advanced Tab click on "Shutdown."
You will then be given the option of rebooting or shuting it down.
 
Unfortunately, if the other comp isn't running Win2K or you don't have admin access, then you will have to use another program.

Preatorian: can I do this over the internet, or does the computer have to be on my network??
because the computer I want to remotely shutdown is over the internet, and is in fact running win2k professional final