Depends what you're going to use it for. Best would be a "lossless" file format such as FLAC, Monkey (APE), or Apple Lossless which will not lose any sound quality in the conversion but will be between 40-65% of the WAV size. Alternatively you could convert it back to mp3 or aac but that would mean a loss in quality because each time you convert or reconvert a song into mp3/mp4 audio ("lossy" formats) then it will throw away audio information to during the conversion process. If you're not fussy about sound then go this way. But please don't share such a reconverted file on the gnutella network. I'm sure you wouldn't want to downld a song that had been reconverted 10 or 20 times so all you end up hearing is distortion. lol The gnutella network should only share direct cd rips to mp3 or mp4 or wav, etc.