Best Option is OpenOffice's Word Processor. Work's very easily to create, and to save as a PDF. Allows you to easily intergrate your pictures for your front cover. (Hint, hint..) Download this one at
http://www.openoffice.org
PDF995 at
http://www.pdf995.com has a free converter that works very well also. You just print to the PDF Printer.
Another option is CutePDF, it works much like PDF995. It can be found at
http://www.cutepdf.com
Those are the 3 options I've used for many items, and have installed many times for clients.
Note: If you already created your document in Microsoft Word, you can easily open it in OpenOffice, and then save as a PDF file. Your learning curve in OpenOffice will be almost zero, since it works very similar to Microsoft Word.