Text-To-Speech softwares can read text files in format of .txt
and .doc with natural voices.

The  Text-To-Speech voice engine on Vista is Microsoft Anna,  and
Microsoft Sam on the Windows XP, Microsoft Anna  on vista speaks more
clearly.

You can find what voice engines have been installed on the computer by
following Control Panel->Speech->Speech Properties->Text To Speech tab-
>Voice selection drop down window. The voice of Microsoft Sam has been
installed by default on Windows XP, and Microsoft Anna on Vista. You
can install other voices too.

The Microsoft's narrator and panopreter [http://www.panopreter.com]
are 2 freewares.  Panopreter is an easy-to-use tool which reads files,
typed words and converts files into wave and mp3 files.  Both are
useful tools.

If you don't like to sit at the table looking at the computer screen
for a long time, you can try to use these softwares. Or if you are
learning languages, the Text-To-Speech softwares are good assistants.