LyX - A WYSIWYM document processor.
LyX is a document processor that encourages an approach to
writing based on the structure of your documents (WYSIWYM)
and not simply their appearance (WYSIWYG).
LyX combines the power and flexibility of TeX/LaTeX with the
ease of use of a graphical interface.
This results in world-class support for creation of mathematical
content (via a fully integrated equation editor) and structured
documents like academic articles, theses, and books.
LyX requires a working installation of TeX/LaTeX. For this you
may install Texlive packages available here or from Texlive DVD.