You can use VLC Media Player to play ogg files.
I think VLC ( www.videolan.org ) will do it. I was just playing with some of the transcoding feature within VLC this morning.
P.S. I am sure there are audio specify opensource apps on www.sourceforge.net .
You can find a list of of other ogg file players and encoders at vorbis.com.
Thanks for the quick responses!