I used the Dragon Naturally Speaking software some time ago and it was more trouble than it was worth. My laptop has Windows voice recognition software which comes with Vista but it is really only best for giving commands, 'open document', 'close document', etc.
Although I understand that voice recognition software has come a long way since its inception, it is still rough around the edges. Google Voice uses recognition software to send voice mail messages and it is consistently incorrect that I end up listening to the message instead of reading the text message it sends to me.
Here's a product review on the Dragon Naturally Speaking but I'm sure you can find other reviews, perhaps on Cnet.
http://www.consumersearch.com/voice-...ition-software
Janine