PDFCreator is a completly free open source application for creating PDF documents from almost any windows application that is capable of printing. You can even create files other than PDF like PNG, JPG, TIFF, BMP, PCX, PS and EPS.
Another good feature of this software is that you can merge multiple files to convert them to a single file. This software also can protect files with passwords and also encrypt them. There is also an autosave option.
The interface is pretty simple. Chose the document from the add menu and then convert the files or email them after converting.
Operating System: All 32-bit MS Windows (95/98/NT/2000/XP).