If you were looking for a way to dictate to your computer without buying Dragon Naturally Speaking and didn't want to fuss around with training your version of Windows on how to interpret your voice, you might be pleasantly surprised to learn that Google 's web speech api seems to be a part of their standard (free) Google docs software.
Unlike the web speech api, there is no 400 word cut off.
I did some testing with my Windows 7 laptop with a Core i7 Intel processor over a wireless connection and you can see the results for yourself in this short video.