i use the one embedded with ms office product, works pretty good for me! let you choose menu and browse the list and stuff....
microsoft had one...i'll see if i can post it..but i've used it with good success and i also use it for my mobile and works damn good.
There's a slight learning curve. It becomes helpful and easy if you can train yourself to speak in a way that the program understands. Can't speak to it like you would a friend. Tried it, but I never got use to it, just felt weird... feels like mouse and keyboard are still the way to go.
i believe word 2002 and above also has a speech command like it types what u say automatically .... its pretty $h!t haha
IBM viavoice Dragonsoft Naturally speaking.. Dragon naturally speaking is wayyy better, but its expensive. Via voice is a little more affordable, but its less accurate. Free ones? Im not sure, linux has some free ones. PM if you want tools or such, i'll see what i can find