Comparison of Dragon Naturally Speaking and Microsoft
I just came across this recently published comparison of Dragon Naturally Speaking 8 and the dictation engine Microsoft ships with Office 2003. This is one of the most indepth comparisions of these products I've seen, and if you are about to spend a significant amount of effort training and using one of these products you'll want to read through this and understand the tradeoffs.
The main take away here seems to be DNS8 offers better accuracy than Microsoft, but also requires a LOT more CPU. The author also points out that both products do not seem to perform any better/worse on dual core machines. This sort of suggests that if you've already bought Office and are running on a low end or older PC, you might want to just use Microsoft's engine. On the other hand if your PC has ample MIPs available and you have $$ burning holes in your pockets, go and buy a copy of DNS8.
The author's findings do gel with my own personal experiences in the recent past, when my right arm was in a cast for 6 weeks. I started out with the Microsoft dictation engine and after a couple of weeks I switched over to DNS. My main motivation for switching to DNS was not recognition accuracy, but the fact that they also offered a speech interface to the over all windows desktop, which let me use the computer with minimal need to try using the mouse with my left hand. Once I got DNS trained and running, I felt it offered more accurate dictation as well, though I didn't try to objectively quantify performance as this article does.
Another thing to consider is that with Windows Vista reportedly supporting speech as a seamless platform feature vs. an afterthought, its quite likely purchasing DNS at this point could be a waste of $$. I would expect the speech engine(s) in Vista as well as how they are integrated into the desktop and applications will be significantly better than what we've seen in the past.
Read the article.