I think Hitch answered this elsewhere (there's no need for multiple posts, if that was you). But in case it wasn't you, I second her recommendation for Dragon Naturally Speaking. You must train it to understand your voice, and perhaps adapt your voice to it, but it can come very close.
(Don't trust KDP to publish a print edition. Don't trust CreateSpace to publish an ebook.)
Hello, I might suggest an alternative as well: I've been all over lately and pretty much the only thing I always have with me is my phone, so I bought a decent carbon-tipped stylus and downloaded the Google Handwriting app. It translates your handwriting into text, and it's scary-accurate, even if you write in cursive. There are issues when editing afterwards, namely it sometimes joins words, but otherwise it is a very effective way to write on the go. I like to go to bars and sip on a beer while I'm writing at the same time.