Install NX Server NeatX on Ubuntu 11.10

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:freenx-team

As long as oneiric is not in the list of you have to tell your packages sources to download and install the packages for lucid 10.04:
sudo sed -i 's/oneiric/lucid/g' /etc/apt/sources.list.d/freenx-team-ppa-oneiric.list

sudo vi /etc/apt/sources.list.d/freenx-team-ppa-oneiric.list
sudo apt-get update
sudo apt-get install neatx-server