I haven't tried it extensively but i hear xvoice is a half decent one, i think it works with most X applications. That of course means you will hopefully be using the console strictly from X if you plan on being totally hands free.
Also, if you are someone or are installing this with special needs that needs to be able to control the OS from the regular, non-gui console, I think your better off with a "voice keyboard" (cant remember what they are called exactly) than having the software handle it, i am not sure if are out for retail use but I've heard of them being used at some universities.
I dont know if this really helps, but hopefully it might point someone in the right direction if it doesn't help you. I mainly posted as an answer because this was too big to be posted as a comment (or even 2 comments!).
PS: you could use xvoice, and use it ON TOP of virtualbox, and then control everything that way, which is fine if you have the virtualization extensions that most CPUs/GPUs/APUs offer these days (the newer the better). As far as commercial software goes, i cannot recommend any of them because they never seem to be anywhere near good enough for the price and require a rediculous amount of training...uck