The main difference is that .Mp3 is compressed file so the file size size is reduced (around 4Mb for 4 minutes of 16bit 44KHz stereo audio). While .WAV is uncompressed and the file size is larger in size (around 40Mb for 4 minutes of 16 bit 44 KHz stereo audio). The disadvantage of .MP3 format is that because the audio is compressed the quality is slightly reduced to the trained ear (high frequencies 3Khz and up). Also, your CD player will not recognise this format and you will need to convert it to .wav format. The main advantage is that new technology has allowed us to play this format on either DVD players and there are also MP3 players for your car or even carry a portable mp3 player. Now get this, and the storage capabilities of such devices can allow you to store up to 1000s of songs, and you can erase and download more songs if you get bored of them, cool huh! I am fortunate enough to have an iPod (Apple Macintosh product) that allows me to store 2000 MP3 format songs, the cool part is that once I have downloaded a song (usually around 1-2 minutes with Cable) it takes around 2 minutes for 1000 mp3 songs to travel to my iPod portable player from my laptop, using FIREWIRE, but thats a different topic all together. The power of Technology, its wonderful dont you think!