I've used (using) Dragon Naturally Speaking 5.0 and it works reasonably well.
The most important things to remember are to invest in a very good DIGITAL headset/michrophone. For acurate voice recpgnition you need the best or you will spend more time correcting mistakes than if you would have typed the text in the first place.
Next invest the time to "train" the software to your speach patterns and/or special needs. By this I mean that the software needs to learn the type of words and jargon used in your particular proffession or activity.
After that, the software is pretty accurate.
Have fun.