As you surely know, XP is a single-user OS which means that there can be only a single user logged-in at one time. If the administrator logs in from a remote machine using the remote desktop tool, the current user is logged off and a message shows up saying "this machine is currently in use [...]"
If you have a spare 3 minutes, try to reproduce following steps:
- Log into a non-virtual Windows XP
- Use Virtual PC to boot a virtual Windows XP and log into it
- Use remote desktop in the virtual Windows XP to log back to the non-virtual Windows XP (which hosts the virtual one)
What happens to your non-virtual Windows session after you log into it from the virtual machine? Will the "this machine is currently in use" message show up?
Well, if you do it using two XPs, the host screen goes black and the machine stops responding. The non-virtual XP is controlled "from the inside".
What's great is that the non-virtual machine still runs - you can access all it's services, the application server, the database server and others run perfectly. You just cannot control the machine anymore using the keyboard.
I belive that there are few other interesting options to continue this experiment.
For example, can you regain the control of the OS by accessing it with the remote desktop from yet another machine? What happens when the Windows Server 2003 is used instead Windows XP?