How to manage remote Xserver from local gdm?

[Remco Poelstra <r j poelstra student tue nl>]

Hi,

I have gdm running on my PC and on my laptop. Now I want that my laptop 
shows up in gdm on my PC when it's available, so that I don't have  to 
start x on my PC and use vnc to connect to my laptop.
I've enabled XDMCP on both systems (and it works with vnc), but my 
laptop doesn't show on my PC.
I've tried to some howto's but I couldn't find the answer there either.

Is it possible to do this? If yes, how?

Thanks in advance,

Remco Poelstra