I am experimenting with some Ubuntu 9.10 VMs. Here are a few of the initial setup
steps:

sudo apt-get install openssh-server

then install vmwaretools

sudo nano /etc/apt/sources.list

-----Add the following lines-----

deb http://ppa.launchpad.net/marceloshima/ubuntu karmic main

deb-src http://ppa.launchpad.net/marceloshima/ubuntu karmic main

deb http://ppa.launchpad.net/freenx-team/ubuntu karmic main

deb-src http://ppa.launchpad.net/freenx-team/ubuntu karmic main

sudo apt-get update

sudo apt-get install freenx-server

sudo cp /etc/nxserver/node.conf /etc/nxserver/node.conf.old

sudo nano /etc/nxserver/node.conf

# The base display number from which sessions are started.

#DISPLAY_BASE=1000

DISPLAY_BASE=1xyz (replace XYZ with something)