Can someone give me a quick explanation on all this? Ive been using mp3's for years and have always burned my CD's to 320 or when downloading them chose the highest bitrate possible. Highest bitrate means best sounding, correct??? What is ACC and why does iTunes want to convert it to 128? please advise.. I have about 10 gb of music that I have not converted and im wondering what is the best way to maintain my music library. btw, im on windows 7 if that makes a difference.