music formats and iPod

[Craig White]

now that I've ripped 3000 songs from my cd's I'm beginning to wonder if
I made a mistake by having the default format AAC (Apple's format).

I can export the music using gtkpod but I can't see a plug-in for xmms
that plays .m4a files (I presume that this is Apple's AAC) and I REALLY
don't want to start over...It's taken me a long time to get this far.

Any ideas about what is the best way to handle these things? 

Craig