Winamp is probably the most widely used software to play music in computers.it plays most of the formats around.Real format (.rm)is one another popular format (runs in real player)which winamp does not support.I found a interesting plugin/software which enables you to play real media files in Winamp and Windows media player and it is Real Alternative .get it here
http://www.free-codecs.com/download/Real_Alternative.htm
4 hours ago