Some useful links for using LaTeX:
http://tug.ctan.org/tex-archive/info/latex4wp/latex4wp.pdf the document "LaTeX for word processor users"
http://www.stdout.org/~winston/latex/ a single-sheet quick reference card for LaTeX
http://www.ctan.org/tex-archive/info/lshort/english/lshort.pdf A "short" PDF file tutorial
http://www.ctan.org/ the home for TeX and LaTeX packages
http://www.andy-roberts.net/misc/latex/index.html A nice online tutorial
http://authors.aps.org/revtex4/ the APS RevTeX 4 page with samples and documentation
http://www.uic.edu/depts/accc/software/tex/amslatex.pdf the AMS-LaTeX reference
Software Links:
http://www.miktex.org/ MiKTeX (a LaTeX distribution for Windows)
http://www.xm1math.net/texmaker/ Texmaker (a LaTeX IDE for all platforms)