I am used to LaTeX + Aquamacs for writing papers. I tried to reproduce the same environment on Ubuntu Karmic. The easiest way to do that:
This is a hell of a download (~500MB) so wait.
To enable Reftex and Flyspell in emacs add the folowing to ~/.emacs file:
and this is pretty much it. Now when you open a .tex in Emacs file you will see LaTeX and Ref menu.
BTW, gedit is not bad for editing LaTeX files too but not as many features as Emacs has and no in-text preview of the formulas.