FreeNX is a system that allows you to access your desktop from another machine over the Internet. You can use this to login graphically to your desktop from a remote location. One example of its use would be to have a FreeNX server set up on your home computer, and graphically logging in to the home computer from your work computer, using a FreeNX client.
Installing the FreeNX server on Ubuntu 9.10 (Karmic)
Open your terminal from Applications->Accessories->Terminal
Run the following commands
sudo add-apt-repository ppa:freenx-team
sudo apt-get update
sudo aptitude install freenx
Now use nxsetup to install necessary files and create the special user "nx"
sudo /usr/lib/nx/nxsetup --install
FreeNX Client installation in ubuntu 9.10 (Karmic)
If you want to install opensource client for freenx use QTNX,QTNX NX client for QT install qtnx using the following command
sudo apt-get install qtnx
Install Freenx client in windows
You can download freenx windows client from here and install.