To use VNC in Zurich you have to start a vncserver.

vncserver -geometry 800x600 -depth 16 :1
Log file is <some path>

read this logfile and look for the connection parameters:

11/11/2010 11:45:46 Listening for VNC connections on TCP port 5901
11/11/2010 11:45:46 Listening for HTTP connections on TCP port 5801
vncserver -kill :1

To connect from outside you have to use VPN.