Terminal Server Question

[Microsoft News]

Anyone knows how to find out how many instances of Terminal Server is
running? If I have a Terminal server that has 5 licenses and 4 user's logon
I want to know how to find out that 4 users are logged on. I'd like to do
this all through code. Right now I am using VB.Net and trying to keep track
of how many instances of my application is running.

However, that does not work if the users logon with different usernames.
Example: John logs on to the Terminal server with the user name John and
runs HelloWorld. Then Mary logs on to the Terminal server with the user
name Mary and runs Hello world. Normally you can check the Process ID of a
running exe and see if it is already up before letting the program run
again. This does not work when Mary logs on with her own username to the
terminal server. Now if Mary logs on with the username John then try to run
the application then the process ID code will tell her that another process
is running.

So I have two questions, how do I access details about a Terminal server
through VB.Net? Is there something built in the framework of .Net for this?
If there is something can that help me find the number of instance and what
different user instances are currently running?

Help would be greatly appreciated!!!!!!

Thanks

Clyde