I've read that foobar2000 can run under Wine:
http://www.hydrogenaudio.org/forums/index.php?showtopic=54933
foobar2000 is one of the few reasons I keep an XP box running at home; with 10,000+ songs I just don't want to mess with something I spent lots of time customizing to get working just like I want. It's a phenomenal program and can handle basically any codec on the planet; if you haven't given a go at it before, it's worth a look. I don't know if anything in Linux is quite to the point where foobar2000 is yet, since there is so much discussion about getting it to run under Wine. I'm sure someone will let me know if there is. :)
Mark