Natural Reader 7 has a free version which read aloud any text such as Web, Word, Emails, PDF and more. It does a very good job of text to speech from anywhere on computer. It provides a nice minibar which will just let u select the text and read it lout. No need of copying. All you have to do is select any text and press one hot key. Due to licensing issues, only Microsoft voices are included in free version.
It works on windows 98/Me/NT/2000/XP/Vista. Download NaturalReader Free Version