I am having a Ubuntu fiesty and had trouble with exporting X windows onto my machine. Then found this thread that said this:
X is probably not listening for network connections because of security reasons. The usual way is to use X forwarding facilities of the ssh client
(see -X or -Y option in man ssh).
If you want to enable network connections anyway, edit /etc/X11/xinit/xserverrc and remove the -nolisten tcp part.