We prefer the .ogg format due to its free nature and superior quality. If you do not have a .ogg player, then try our automatic player. If you get a security warning, it just means that it needs to access the goodvibes server. The stream options will let you manually stream the .ogg or an .mp3 stream, as you wish. For a good windows .ogg player, try VLC Media Player. Even Winamp will, but watch out for nasty spyware while installing.