"Step 1: Take control of the default format
The older versions of Microsoft Office, Office 97-Office 2003), by
default save documents in a family of binary formats with the
extensions DOC (Word), XLS (Excel) and PPT (PowerPoint). Although
these formats are proprietary Microsoft formats, over the past
decade 3rd party applications have developed the capability to read
and write these formats.
"However, starting in Office 2007 Microsoft suddenly switched
the default format to something called Office Open XML (OOXML).
This format is not widely supported outside of Office 2007. So if
you save a document in the OOXML format you make it harder for
anyone else to read your document unless they are also using
Microsoft Office 2007. In almost all cases, the same document, if
saved in the legacy DOC format will be more interoperable. Staying
with the default choice, OOXML, only restricts your choices and
make you more dependent on Microsoft Office. Of course, that is why
Microsoft made OOXML the default format.
"The first step to liberate yourself from Microsoft Office
dependency is to change the default format in Microsoft Office 2007
away from OOXML and back to the early binary formats supported by
Office 97-2003, which are widely supported by 3rd party
applications. This is a neutral step that preserves the status quo.
By making these changes you will still be able to read and edit any
OOXML documents that are sent to you, but all new documents you
create will be saved in the more widely supported DOC/XLS/PPT