Use of MSG.exe

I work in hospital that has a lot of workstations and few IT folks to support them. One problem is that workstations get moved and we don't know their physical location. I used to be able to send a "net send" console messge and ask the logged on use to call the help desk and report the location of the workstation they are using.
 
But with the deployment of Win7 "net send" has been deleted. Console messages no longer work. I have been using Powershell for various tasks and know there is a "MSG.exe" applet to send mesages but:
1. I cannot find a good reference with examples.
2. I need a "box" to appear on the users desktop not something in a corner.
 
I need a place to start such a good reference/example for "Msg.exe."

If each floor has a switch on a different subnet, I could give you a script to return the computer's rough location if you want.

Never used MSG.exe sorry.

But how about this as an extreme measure to get attention. (I take credit of thinking of it just now)

Message:- IT have detected this computer has been moved or stolen. Please email helpdesk@xxx.com this computer's primary user, phone number and room number to remove this message.

Program:- ShutDown.exe

Delay:- Something ridiculous like 57600 seconds (Give them 24 hours to respond)

Cmd:- shutdown -i

Run it by your boss first so you don't get sacked. The message remains on top of screen so the user can't miss it and cant ignore it because of it's nature.

Your  reply while interesting does not help.
I am trying to find a workstation not create a crisis.

Thanks for your feedback.

Me personally I will suggest it as an option to my boss who is always stressing over missing computers that need to be found and returned to the leasing company. If you are intelligent with specifying the correct message and time delay, then I can't see how that will create a crisis? I bet you did not even check the application. 

Shutdown.exe is not even worth scripting considering the GUI is so good.

Fortunately we have tools like SCCM that tell us the last user and date who logged into a machine so we can email/phone the user directly.

Also I have given my boss a script that he can type in the machine's barcode and it returns in plain English the building and floor so he can start a physical search.

Finding a missing machine is an old problem with many technological solutions now. But popping up a message box that the user can instantly click off and hope they will phone you is an half hearted attempt in my opinion. The user has already broken the rules and moved the machine.