I am hunting down different expander software types that are compatible with Windows 7. I have run across a few that I can pay for with a yearly subscription, or a never-ending subscription usually running above $150 (eee!). I have found a "freeware" program called WordExpander (http://www.wordexpander.net/) and it seems like it would be suitable for medical transcription.
What expander software have you tried out/like/recommend?