I've spent a ton of money on various solutions to this and have concluded the best answer is iDictate.org - you get a toll free number and live transcriptionists who can turn around your work in under two hours (if you pay a rush fee) and no more than 24 hours with the standard fee.
The human element is extremely forgiving. If you make a mistake, you can simply say, "Er, scratch that and start with . . . " I tried that with the voice recog softwares and it NEVER worked.
I use them for short jobs, like transcribing a letter I dictate while taxiing into an airport, and for longer jobs such as the notes from an entire two-day brainstorming clinic. Clients have been very impressed with the speed of my turn-around time.
They can take MP3s of speeches I give and transcribe them into hard notes, which I then edit into book chapters. Incredible service.