I know this will get me downgraded but the Windows 7 Speech Recognition is probably the best I've ever used.
OS X was amazing until Windows 7 came along. I'm not trolling here, it really is something that is useful and not just a 'toy'.
It is not just the recognition but how you navigate opening applications, browsing websites, and just using your voice to navigate the OS and the applications.
I have many colleagues that use it with Word when they are working with lots of papers and want to dictate information into Word.
If you have a chance to play with it under Windows 7 you should try it. I have felt like Apple set the bar pretty high with OS X, then Windows 7 added some very nice features, so I hope Apple further improves on it.
Cheers!
-P