Windows 2K or XP communications

I would like to ask anyone about what kind of protocol or way the Win OS use in order to allow another PC to access its services….

EX: i have a win 2k machine that i would like to access using ethernet protocol with a dumb pc (like a thin client or terminal). In the same way old mainframes used to be accessed by dum terminal.

Could it be done with an embeded pc with an RTOS (like Linux) just to send back and forth the images and keystrokes????

Any thoughs??/ thank you
jriofrio@hotmail.com