Well if you have an old Mac lying around (or if you use a Mac emulator that can run PPC code, ie not Basilisk II), then Apple's Speech Recognition software is great. It still holds its own even after 10 years of existence with no changes!
Office XPand 2003 come with speech recognition software, I think. While it won't handle anything besides typing words, it does this beautifully.
Kurzweil VoicePad is OK. It came out if 1997 but it still works well after you train it to your voice.