i have to second this suggestion. you can do exactly what you're looking to do in itunes. nothing else to download, and it really couldn't be simpler. further, after selecting start/stop times, you can re-encode for a new track just for your mp3/aac.Well you could use Garageband which is part of the iLife suite. However I end up using the start and finish time adjusting features of iTunes for my ring tones. Get Info on a selected song from the File menu and under the Options tab, you can change where the song starts and finishes.