About MP3's

MP3 is an audio-specific compression format. It provides a representation of pulse-code modulation-encoded audio in much less space than straightforward methods, by using psychoacoustic models to discard components less audible to human hearing, and recording the remaining information in an efficient manner. Similar principles are used by JPEG, a lossy image compression format. The MP3 format uses a hybrid transformation to transform a time domain signal into a frequency domain signal: 32-band polyphase quadrature filter. 36 or 12 tap MDCT; size can be selected independently for sub-bands 0...1 and 2...31. Aliasing reduction postprocessing. MP3 audio can be compressed with several different bit rates, providing a range of tradeoffs between data size and sound quality. The MPEG specifications support Advanced audio coding (AAC) from MPEG-4 as MP3's successor, although other new audio formats have also achieved similar usage levels. However, MP3's extreme popularity makes it secure in its dominant position for the near future, with support from a huge range of software and hardware, including portable MP3 players and even some DVD and CD players. The large MP3 collections that many individuals have amassed will also ensure its longevity, in the same way as with any physical medium.
You can download MP3's from many popular sites such as Napster and Itunes. Look for the right service and you can find exactly what you want out there.