The following products will allow you to create PDF files for free:
- CutePDF Writer - also requires that you install Ghostscript converter which is available from the download page
- Pdf995 - also requires that you install Ghostscript converter which is available from the download page; displays a sponsor page in your web browser (popup web ad) each time you run the software unless product is registered at a cost of $9.95
- PDFCreator (open source development) - Downloading version 0.8 requires that you install Ghostscript converter which is available from the download page; however, version 0.7.1 has the Ghostscript converter built in
All the products listed rely on Ghostscript to produce PDF files, its just that some of them already have Ghostscript built-in to the installer.
Although it is not necessary to know what Ghostscript is, more information about it can be found in the Ghostscript FAQ available here.
Once you have installed one of these programs, it creates a new windows printer for PDF creation. So from within your document, simply choose this PDF printer and it will prompt for the filename and VOILA!
Of course, be sure to checkout DWF files if your considering plotted drawings.