Roxio, and other "BurnWARE" (NERO etc...) will decode your mp3's on the fly and burn them as a standard audio track, this however eats up 10 times the space on your CD. This is a good thing for most people, because it makes the software easy to use, since most people just want to hear the music regardless of the player they put it in and do not care about saving disk space, because CD's are cheap, but for the die hard technogeek who wants 200 tracks per CD you will need to bypass this little helpfull feature and copy your mp3 files as "DATA" and this way they will not be decompressed and you will fit more tracks on each CD for exclusive use on a mp3 player. A mp3 player is different from a standard CD player because it is capable of decoding compressed mp3 files.