Sorry Sasler; didn't mean to imply anything. We've had a lot of relatively nontechnical users show up lately so I've been trying to explain everything as 'least common denominator' as possible.
I did a bit of searching around and it appears that the Maemo-Extras repository has a telnet client. Additionally, this telnet client from the garage _might_ work.
Of course it's possible that there's a problem in the version of vncviewer you're using. Was it in the default repositories? I know there are several people who are apparently using vnc from the 900, but I don't know where it came from. Anyone with an n900 and working vnc care to speak up? As a temporary alternative, I believe there's an rdesktop client available as well since you're working with Windows machines. Oh, here's a link to a vncviewer that's supposed to work.