DirectShow FilterPack is a lite-weight package of DirectShow media filters which, together with ffdshow, will enable you to play many different kinds of encoded/encrypted audio and video with your favorite DirectShow Media Player.
By default Windows is capable of playing MP3 Audio (MP3-files) because of the "MPEG-1 Stream Splitter" and the "Fraunhofer MP3 Decoder" which are shipped with Windows. But unlike MP3, Windows doesn't know how to handle Vorbis Audio (OGG-files).