AIFF is lossless and huge as well. You can select the format and bit rate and CD insert behavior in the preferences somewhere, I think under the "Importing" tab.

I would recommend you always use MP3 when ripping CDs, but make sure to set the bit rate high 192kbps or higher. The higher the bit rate, the better the sound quality, but at a sacrifice of size. MP3 is the standard format that will play on any player and any OS. That's why mp3 players are called "MP3 Players". The only time I would use another format than MP3 is if I wanted to make a high quality compilation destined to be burned back onto a CD for CD audio players, like a mix CD for your car or something. Then, use a lossless format such as AIFF or WAV which don't compress the music, so you get the pure unadulterated sound of the original, but the files are very large. All other formats MP3, AAC, WMF compress the music (and shrink the file size) but at the cost of sound quality. If you compress them too much, you hear a swirly or muffled or pulsating tone.

The most important thing to look at purchasing music downloads. iTunes Store is very popular right now, but you need an iPod to play the music you download. If you purchase anywhere else, such as burnlounge.com, you will get WMA which won't play on an iPod. These files are encrypted with some type of security, which may not be work on various types of players. And you can't legally convert either type of purchased download to a MP3 format that will play on any player. Remember when those little things used to be called "MP3 Players"? -- modified at 17:17 Friday 3rd February, 2006