Ahh, finally found it:
http://www.nomachine.com
That does exactly what I want, it works like a charm and the responsivity is remarkable, it feels that Im actually sitting on the native machine even that Im connected over VPN and ADSL
!!
If the connection breaks, the KDE session is suspended and I can reconnect to it and continue where I was without loosing anything. I can also suspend the current session and resume it from another client, very handy when I work in different locations with the same project
.
There is a free version available as well but I haven't tested it (yet):
http://freenx.berlios.de/