FreeNX - Community Ubuntu Documentation 
$ gksudo gedit /etc/apt/sources.list
deb http://free.linux.hp.com/~brett/seveas/freenx feisty-seveas freenx
deb-src http://free.linux.hp.com/~brett/seveas/freenx feisty-seveas freenx
$ wget http://free.linux.hp.com/~brett/seveas/freenx/seveas.gpg -O- | sudo apt-key add -
$ sudo apt-get update
$ sudo aptitude install freenx
$ sudo nxserver --adduser username
$ sudo nxserver --passwd username
$ sudo nxserver --restart