The English Transcription Editor PhoTransEdit is a free Windows tool to make written transcriptions easier. All you have to do is to enter the text to be transcribed in regular orthography and to press the button 'Transcribe'. If all the words are found in the database provided, the transcribed text appears on the screen. You can then copy and paste it into your word processor.
Here's a screenshot:
http://www.photransedit.com/ is where you can read more about it and also download the installation file.