Through my years in IT support I have tried out a few different free pdf writers. The easiest one that I have used so far has been CutePDF Writer.
CutePDF works just cheap nursing shoes like a regular print driver on your computer. All you need to do is select CutePDF from your printer list when you go to print it and print it. It will then ask you for a place to save it.
After that you can then distribute your pdf file however you want. CutePDF Writer leaves no watermark or evidence of itself on your final pdf document. It also leaves no adware or spyware on your computer that I can find, and there are no advertisements displayed when using it.
CutePDF writer is free for personal and commercial use and only has one option for saving your pdf documents. If you are looking for more options you can purchase CutePDF Pro on their web-site.
Just a note: When installing CutePDF you will need to have Internet access as it needs to download a PS2PDF converter. The installer handles this all by itself as long as you have Internet access.
You can download CutePDF Writer at their Website: