Include LXDE in XUbuntu as XFce alternative

I believe that the goal of Xubuntu (in https://wiki.ubuntu.com/Xubuntu) to develop an Ubuntu derivative with low system requirements can be better served by allowing the underlying desktop environment to be changed from XFce to LXDE perhaps as a GDM alternative or as the new default desktop. LXDE (http://lxde.sf.net) is an even less resource-hungry environment capable of emulating the basic GUI features of a typical Ubuntu Desktop. LXDE can be a drop-in replacement for XFce since LXDE also uses GTK 2.