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.  Mouse 
over the icon to see the Display number (you should see something like 
"Display=0").  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, connect to 
lab.cs.stevens.edu. 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:DISPLAY_NUMBER

    so for example, 
    export DISPLAY=123.234.212.122:0

Then run your programs (try xterm or netscape)