I occasionally want to use my Ubuntu machine as a desktop but mostly as a headless file server. Before I upgraded to Oneiric, I used rcconf services to disable or enable the desktop. In Oneiric I don't see GDM; so can't uncheck it. LightDM appears but isn't checked. I don't see anything else that looks like a desktop.
So, how can I disable, an occasionally enable, the Oneiric desktop?