I use
MikTeX combined with the
Eclipse editor/IDE. You can download all of this for free. It may be a bit tricky to set up if you haven't used it before, but it's really good once you have it working and you are comfortable with LaTeX.
If you don't want to bother with configuring MikTeX and Eclipse, there are also online LaTeX deployments that can output PDF and/or image files. For example:
ScienceSoft.at and
Latex-Online-Compiler. Some other online LaTeX resources are available at
Wordpress.