Hello So you want a better remote desktop program with better compression than VNC and encrypted communication.
Follow these steps to install FreeNX
After install Backtrack 4 or 5 on to your hard drive or what ever USB/Flashdrive you will want to do the following.
1. Give your Backtrack OS an IP address to get to the internet
2. Run this command. apt-get update
3. Run this command. dpkg-reconfigure openssh-server (This will generate your keys)
4. Open up Firefox and goto http://www.nomachine.com/download-pa...p?Prod_Id=2961
a. Download all three packages to your Backtrack OS (Client, Node, Server)
5. Install them in this order with this command
a. # sudo dpkg -i nxclient_3.5.0-6_i386.deb
# sudo dpkg -i nxnode_3.5.0-3_i386.deb
# sudo dpkg -i nxserver_3.5.0-4_i386.deb
6. You will need to have Backtrack start in to the KDE Desktop automatically
a. Run this command vi /etc/rc.local and add su root -c startx
Note: Now we have to tell FreeNX where the new location of the startkde file is at normally it would be /etc/X11/Xsession startkde but this being Backtrack it was installed at /opt/kde3/bin
7. Edit the following file, vi /usr/NX/etc/node.cfg
a. Comment out the original command #CommandStartKDE = "/etc/X11/Xsession startkde"
b. Now add a new entry CommandStartKDE = "/opt/kde3/bin/startkde"
Now save your settings and exit vi editor (:wq!)
8. Now you will need to open vi editor again on the server.cfg file
a. vi /usr/NX/server.cfg
You will want to edit
EnableSharingDesktop="0" to be 1
EnableFullDesktopSharing = "0" to be 1
EnableAdministrativeLogin="0" to be 1
This will allow root to start the session.
9. Now you may install FreeNX client on your windows box or Unix box which over you desire.
a. Configuration for the client is as followed.
i. Enter in IP address save password if you like
ii. Session settings Unix and KDE
iii. Pick your resolution most are 1024x768
click save and enter in username root password toor and login.

Hope this helps some out there

Thank You