The remote desktop function in ubuntu is a nice handy one, to enable it from terminal
first ssh to the server you wanna remote desktop, then install tightvncserver
sudo apt-get install tightvncserver
then run it
it will ask you to set a password for using this option and it will return the x desktop id.
Now go to Applications -> Internet ->Remote Desktop Viewer, and enter the address of the machine followed by the x desktop id like this :
where 1 is the x server id.