I recently reformatted my system for the first time since I originally installed Ubuntu 11.04 on it, and I want to document some of the "gotchas" I encountered. I unnecessarily lost a few hours to trial-and-error, and I hope to spare you the same frustration.
For this rebuild, I personally installed Lubuntu (with an "L") 12.04,
because I hate Unity, and because
gnome-panel shares too many of Unity's
constraints (like only supporting four workspaces) to be useful. With that
said, I'd imagine that the following advice applies to some of the other
*buntus as well.
This was the process I used to install Lubuntu 12.04 on a clean system: