You cannot telnet (or ssh) to guinness or the netBSD machines and run a graphics 
program.  You must either run the program in the lab, or you need to "export" 
your display.  If you are running Windows on a PC, there are a number of 
programs for exporting X-windows programs.  Below are directions from a former 
student regarding one of these packages.

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One of the better packages for exporting X-windows programs to windows machines 
is X-win32 5.4     You can download a trial version from http://www.starnet.com/ 
(you really only need a trial version since it runs long enough to test your 
programs).

Run X-Win32 after you installed it and make sure its in your taskbar. Next find 
out your ip address by running cmd from start->run, and typing ipconfig. This 
will give you your 4 number ip address. Next, go into guinness or one of the lab 
machines (dab,murphys, lab.cs, and so on). Make sure you are in bash shell (or 
any other shell that supports export command, or just run "bash"). Enter the 
following: export DISPLAY=YOUR_IP:0

    so for example export DISPLAY=123.234.212.122:0

Then run your programs (try xterm or netscape)