Distance help

Here is the project: Educational program to help people learn at distance. 2 computers (A and B) connected through the internet. The goal of the whole thing is to permit those 2 computers to communicate together and let computer B control some part (mostly text ones) from Computer A in a Windows environment. Computer A has the host program and Computer B the manager one. Could be the same program for versability. The Host program should be able to select (draw) a window over some part of its screen (example: the MSN text window). The Manager program should be able to see and interact with that selected window (e.g.; writing text in the other MSN text window) If the Host change something in the Selected Window, the Manager should see it on its screen (window). Both the Host and Manager should have access to the Selected Window over the internet and in a Windows setting in real-time. Security should be a concern so both programs are passwork protected and don't allow any holes over the internet. We are aware of 'logmein' though that program will do too much and will give access to the whole screen. We just need to access a small window. That window will contain 99% text only (unicode). What is exchanged is unicode text, nothing else. We're looking for something small, quick, fast, low bandwidth. The Manager program should be able to access several Host programs at once and several windows over the same computer.