How to build AWS ubuntu instance with optional KDE

[mahesh]

I would like to build a ubuntu EC2 instance in AWS that works like a server most of the time but when I need a GUI, I can start up the KDE and do some word processing and web browsing, then exit KDE and return to server mode. The reason for this is I don't want to have to deal with VNC and all its security issues. I just ssh into my instance and turn on the GUI when I need it. Is that doable? If so, how?
Thanks in advance.