How to run GUI admin tools remotely?

[Chris G]

I have a backup system in my garage on which I have installed xubuntu
8.10.  It would be really useful to be able to administer it remotely
from my desktop system in my house (also xubuntu 8.10), but none of
the GUI systems/services admin tools will work because of X security. 
I always get something like the following:-

    root at garage:/usr/bin# services-admin
    X11 connection rejected because of wrong authentication.

    (services-admin:7307): Gtk-WARNING **: cannot open display: localhost:10.0

Running *user* programs remotely works fine so I have ssh running such
that X is working OK.  I have also tried all sorts of 'xhosts +'
commands on the local system such that there should be virtually no X
authentication at all but I still get the above error.

Can anyone suggest a way to do this?

-- 
Chris Green