* Lack of codecs 'out the box' leading to a hunt around the net for third party codecs, such as Ogg, FLAC, Mpeg4, H.264 and AAC (which is supported by Microsoft's Xbox 360 and Zune Mp3 player).
* No gapless playback, essential for albums like Dark Side of the Moon and live albums.
* WMP's mp3 decoder's overly strict adherence to ISO Mp3 standard (unusual for MS) forcing LAME 3.98 to encode at 100% compatibility without using the bit reservoir on 320kbit frames