At work we use sometimes a shared computer (Windows XP). Normally we access the software through Remote Desktop. The problem is that there is no way to tell if someone is already connected, if not running for office and asking everyone. Is there a way to know if someone is already connected with Remote Desktop, and what his user name without interrupting its connection?
qwinsta is your friend.
Open a command-line. Type qwinsta /server:machine-name.
It will tell who's logged to the machine. It'll tell you if it's local (console) or remotely (rdp-tcp#xxx).
You can use the Terminal Services manager to connect to the Windows XP machine and review sessions. In this case, there should be two - a console session and the logged in user.
WMI should also expose this information for you, if you need this information available programmatically.
Do you share the computer with a common user login? If not, and everyone is in the habit of logging off and not just disconnecting, you would have windows warn you, that you were about to disconnect so and so and thus you will know both if someone is on the machine, and also who they are, and you can cancel your connecting if someone is using it.
This relies upon everyone having their own credentials, (which is a good idea anyway) and having the good habit of logging off. Can you get them to all see the advantage of that?