I've never used Dragon Naturally. My personal preference for transcription software is Philips SpeechExec Transcribe. I know that Express Scribe is the most widely used, but I've found that background noise, static, etc., are for whatever reason, drowned out in the Philips software. I used Express Scribe for a very long time. When it was time to update my foot pedal, I purchased a Philips, which allowed me to download their transcription program. It doesn't support all formats and you may need to convert WAV files into MP3s. But I believe Philips is constantly updating, so it's a matter of keeping up to date with what's out there. I love SpeechExec Transcribe, and I wouldn't trade it for anything. Check it out:
http://www.dictation.philips.com/index.php?id=70.