Shutdown XP/Vista from Ubuntu

I am running a headless Ubuntu Server 8.10 Intrepid. I have a nice UPS hooked up to it with apcupsd running so the server gets shutdown if the need should arise. However, I also have an XP/Vista (Dual boot) desktop running on the UPS. It would be very nice if I could get the desktop to shutdown when the need arises. So. I know how to edit the apccontrol file in /etc/apcupsd, but... the command?

net rpc shutdown -I 192.168.1.102 -U ubuntu%password

^Returns WERR_OK

So any ideas on how to do this?

If your UPS has software, put the software on the XP/Vista machine. Then this depends on how the UPS connects to the computer. If it has a serial connection AND a usb connection, then use one on one computer and the other on the other computer. If it doesn't have both, then you are stuck.

APC Back-UPS 1500 RS w/LCD
Only a data port which converts to USB.

I'm sure there must be a way to remote shutdown an XP/Vista machine from Vista...

You might check the owners manual for that UPS to see if it is even capable of shutting down more than one machine. Or it could even be something in the APC software that goes on the computer, you plug the UPS into one machine then that one will shutdown all the others through the APC software before shutting down itself, I'm not sure.

Are you aware of the software that I am using?

http://www.apcupsd.com/

It works fine for shutting down my server. But I have the ability to script the shutdown command, and I would like to add a command that would remotely shut down my desktop since it is also on the UPS.

Ah fart, I'm not. I kind of skipped over the apcupsd part of your original post. Normally a UPS comes with a disc and then you can put that software on a server and see the power consumption of all the devices connected to it and it will shutdown the server when the power goes out, I didn't realize you were using a special thing. w0ops!

If you install an ssh server on your XP box(There's one by Vandyke, and a freebie called copssh), you can run this remotely;
tsshutdn.exe.

That will shut down the XP box.

Alright, I did something along the lines of what Daemonguy suggested and installed Cygwin with sshd. Now to set up ssh-keygen to autologin the server and run tsshutdn.exe!