Open Office is an excellent and free office suite. It's the #1 alternative to Microsoft Office, and just last year was downloaded over 100 million times from the creators homepage (link below). It has all the main capabilities of Microsoft Office such as; word processor, spreadsheets, presentations, etc, plus it can do things that MS Office can't such as create and copyright PDF documents. It's also compatible with MS Office so that you can both open and save documents in formats that can be opened/edited with either office suite.

  Adobe Acrobat Reader is the most widely used free PDF reader. It doesn't allow you to create or edit PDF documents, but it's interface for reading them is very easy to use. Check their website for the lastest version.