Does anyone know of a semi-decent "Speech to Text" program?

[Eel O'Brian]

Preferably low-cost.  I know about Dragon NaturallySpeaking, but at $250 that's too rich for my blood.  This would just be for the transcription of audio notes I take during the day while I'm working, so it doesn't have to be extremely accurate - just hit the mark most of the time.  I'm just trying to save some time, basically.

[Eel O'Brian]

I am typing this using Windows Speech Recognition. 

This is pretty badass!

It has some bugs, but works pretty well for the most part.

Can I use mp3s with this?  I can't seem to find the option if there is one.