Hi, 
I just wanted to let you know that there is a "Whiteboard" software for use by those who teach others. It's like having a computer whiteboard that you can write on and you can cut/paste screen shots and then mark them up in real time....non destructive.
 
It was "for cost" but now it''s free.
 
Here is the link:
http://lightools.fredisland.net/index2.htm
 
And here is a demo of it...sorry it's using bibleworks for the demo...but hey! What can you do?
 
 http://www.youtube.com/watch?v=CD0FsNgqXvc
http://www.youtube.com/watch?v=CD0FsNgqXvc