With AUCTeX and preview-latex, you can properly edit your document and equations in their high-level (TeX source) representation, while getting near-instant confirmation that your equations will turn out the way you want. It's pretty much the best of both worlds.
AUCTeX is easy to set up on Ubuntu, although it takes slightly more work than the usual apt-get invocation. Here is a HOWTO for my future reference (and yours). This has been tested on Ubuntu 9.04 with a post-v23-release emacs-snapshot:
$ sudo aptitude install auctex
Add the following init code to your .emacs file.
(load "auctex.el" nil t t) (load "preview-latex.el" nil t t)
Open a LaTeX file in Emacs and press C-c C-p C-b (M-x preview-buffer) to generate math/graphics previews for the entire buffer. After you update an equation, press C-c C-p C-p (M-x preview-at-point) to refresh the preview.