On Windows Vista the speech recognition is built in and works great! I have been utilizing it over the last week and only a few minor issues, like not working to type text here in a forum or elsewhere if using Firefox, and not typing body of mails in Thunderbird, but most
other apps seem to work just fine.

I really like the fact that you can speak in full sentence structure and it accurately understands in most cases even for complex words like know, wind, effect/affect.