If you want to convert a document to PDF you can save it as PDF (File -> Export -> PDF). But what if you have a lot of documents you want to convert to PDF. Then the Office Interop Assemblies could help you. This blog explains how you could use the Office Interop Assemblies to convert Word, PowerPoint and Excel files to PDF.
– Microsoft Office needs to be installed
– Some dev skills
This is not something you would like to use on a large production environment. But if you are in need of a onetime solution this could be a solution. Always keep in mind that you backup your Office documents and check the results after converting.