{ google these } 

2nd Speech Center (personal favorite :)(has pronouncing modification abilities)(sap15)
NeoSpeech SAPI5 Voices
AT&T Natural Voices
Kurzweil 
SayVoice
Speakonia
TextAloud
Text2Go

naturalreaders (free)
http://www.naturalreaders.com/download.htm

Expressivo
http://www.expressivo.com/buy_now.html

ReadPlease 2000
http://www.readplease.com/

DSPEECH : (most recomended)
http://dimio.altervista.org/eng/

NaturalReader
naturalreaders

Balabolka does lots of languages 
Balabolka

smartread only does English and Simplified Chinese 
smartread

Speak Clipboard (Open Source for Windowns XP)
Speak Clipboard