question on x windows

[Aaron Bliss]

Hi everyone,
I have a user who would like to connect to x windows on one of our linux 
servers.  I'm not use to offering up x windows to any end users (I'm a 
command line guy) so I'm struggling with this a bit.  I've installed x 
font server, daemon is running, and I installed xfce.  Server is running 
at run level 5 right now.  I'm not sure what ports I need to open on the 
firewall to allow them to connect to the server or what other config 
files that might be preventing them from displaying an x session on 
their desktop (they have a windows x server running on their machines).  
I know that x windows sessions are insecure, so I would also be in favor 
of forwarding the session over ssh, but I would like to know how to 
connect with and without ssh to the xfs server.  Thanks for your help.

Aaron