Just the terminology problem: if one host requests a screen shot of another one, and the second one delivers the screen shot, no matter what you do, first host is called a client, and the second one a server. In other aspects, all such hosts can play the role of a client, but relative to the screen shot request, they are all servers. This is how actually RDP works, so, this is the first thing you need to learn:
http://en.wikipedia.org/wiki/Remote_Desktop_Protocol[
^].
Please also see these CodeProject articles:
Remote Desktop using C#.NET[
^],
Palantir - Remote Desktop Manager[
^].
—SA