LibreOffice is a free and open-source office suite that is compatible with other major office suites, and is available on all operating systems. It is an independently-developed version of the OpenOffice.org suite.
Sumatra PDF is a free PDF, eBook (ePub, Mobi), XPS, DjVu, CHM, Comic Book (CBZ and CBR) viewer for Windows.
Tree Notes is a notes organizer for Windows that allows you to organize and manage all your notes in a tree structure with icons. Tree Notes is very easy to use and light-weight.