LaTeX is completely free, and comes with most Linux or Unix distributions. You can download a Windows version called ProText at The Tex Archive.
That's brought us the end of our little tour de force of LaTeX. There is a lot more to learn about LaTeX, bibtex and so on, but that's all we have time for here.
If you want to know more there are many excellent resources on the web. Personally I find the most useful to be the Cambridge University Engineering Department LaTeX Guides, but if you look on Google there are many, many more!