I gave up on using 'cmd.exe' and set the shell spawned by the native Win2k telnetd to bash (using a wrapper to setup the environment and prime the file descriptors as per the stdout/stderr bug). This works well and is adequate for the X-terminal session establishment.
I have got word however that there is a working implementation of 'xdm' on Win2K which deserves investigation... > msg, sorry, I don't think NT's telnetdeamon does mount drives and so > on, give cygwin's (rshd/sshd/telnetd) a try, and read the faq how to > get it mount the drives.. and check the cygwin mailinglist, well > discussed question.. maybe even the faq.. >