Natural Reader (Text-To-Speech Software)
Natural Reader is a Text to Speech software which can convert any written text such as MS Word, Webpage, PDF files, and Emails into spoken words.Just need to highlight the word or sentence and Press Control-F9. Click here to view demo . 
Operating systems: Windows 98/Me/NT/2000/XP/Vista/Win7 • Mac OS X 10.4.1
Click the following the link to read user guide and instruction to install into your computer:-