Fenixp: And thank you too, this seems that it would be able to do the trick - not free to download thou, and I'm not THAT eager to play on my TV :D
As I said.. your requirements aren't very clear. You are half asking how to implement a particular solution (duplicate display over network?) while half describing the problem (playing games on a remote display?).
This can lead to the situation where you don't actually get the ideal solution to the goal.
For example, say I wanted to play X3 on my tablet (which is far, far too underpowered). Sharing the display of my desktop while running the game could work, but I would be contending with differences in resolution and such. Instead, VirtualGL allows my desktop to do the rendering at my tablets resolution and just output it across the network to the tablet (and yes, I have done this :]). Meanwhile, my desktop remains otherwise usable because X3 would be running "in the background".