O produto gratuito ZoneScreen pode funcionar para você:
ZoneScreen is a tool for extending your desktop workspace using displays of network connected computers or portable devices like Pocket PC.
ZoneScreen consists of two parts: kernel-mode ZoneScreen Virtual Display Driver which is visible to Windows just as normal video card with monitor attached to it, and user-mode ZoneScreen Wizard which is responsible for capturing image (running at server side), transmitting it over the network, and drawing it at another computer (running at client side).
Existe também um produto semelhante, porém comercial: MaxiVista (US $ 39.95, teste disponível).