double-bridging via ssh

[Dietmar Krauss-Varban]

Ok, so I have tried this a couple of times unsuccessfully.

I need to connect to a machine "c" (actually, two cases: a PC and, 
alternatively, a linux box) that is (are) only accessible via ssh from a 
Unix server "b".  That server is also only accessible via ssh.  I am 
attempting all of this from a Windows 2000 PC "a" at home.

All have ssh installed (working fine), "a" and "c" have VNC installed 
(working fine locally).

So what ssh command(s) do I need to submit from my windows machine to 
establish a tunnel for VNC to work?  All my attempts time out.

- D.