How to play ogg-songs.

For further details: www.vorbis.com

Recommended ogg vorbis players:
For Windows: WinAmp (may be if you got on very old version it doesn't work. Please download download version 2.81 or 3.xx)
For Linux: XMMS
For Mac: Audion

How to encode ogg-songs.

For Windows: CDex
For Mac: Audion