PDF Creator an open source project is a great way to create PDFs for free.
A PDF is a platform independent document with fixed formatting, and once created, it cannot be edited, making it excellent for copyrighted material.
Install it, and it will create a new 'printer'. To create a PDF of a document, go to print the document, and select PDFCreator as the printer. When it goes to print it will ask you where you want to save the PDF.
SourceForge.Net Project site: