PDF995 is one of many free PDF makers. It's only downside is that it puts up a little ad everytime you make a PDF, as well as using Ghostscript, which is still ok for most things.
I like PDFCreator http://sourceforge.net/projects/pdfcreator/
It's open source, free, fast, efficient and has a lot of good features (like the ability to combine multiple documents into one PDF).
In addition to PDF printers, OpenOffice, a free open source office software suite with MSword compatibility, has the ability to save directly to PDF formated files. Its especially useful if you want to include hyperlinks and bookmarks in your PDF file.
I like PDFCreator http://sourceforge.net/projects/pdfcreator/
It's open source, free, fast, efficient and has a lot of good features (like the ability to combine multiple documents into one PDF).
If you're using Office 2007 i'm sure there is an add-on you can download from uncle Bill that allows direct output to .pdf (i'm sure i downloaded it some time ago on one of my pc's?)