LaTeX is an environment for text processing. LaTeX is an extremely powerful text processing system, but can be a bit difficult to learn. LaTeX is more like a programming language for rendering text than a word processor. Word processors have the advantage of ease of use, but often fail to offer sufficient flexibility for the broad range of documents that one might wish to typeset. If you are not averse to raw programming environments, a simple text editor is all that is needed for the production of LaTeX documents.
Avoid it almost altogether by using LyX. I have found LyX useful for .doc type co-authors, but in general find it to be buggy and unfriendly for people who know LaTeX. If you have to compromise, you might wish to give LyX a look. A Win32 port.
Make it easier with syntax highlighting, buttons, and lots of niceties : TeXmaker for *nix or WinEdt. WinEdt also requires MikTeX. For OS X, I use TeXShop religiously.
Repositories: The Comprehensive TeX Archive Network [CTAN]
The Not-so-Short Introduction to LaTeX is very useful.
TeXpower is a presentation creator based on FoilTeX with effects and .pdf output.
TtH is a .tex to .html translator.
a0poster is a LaTeX style file for creating posters.
