M-Audio Sonica =>Zu Pivot or Markertek mini =>Fixup Supermini V6.2 =>Beyerdynamics DT931
For the most part I am pretty satisfied with this setup. However, I recently put together a new desktop system with a D-303 and The Meathead (see sig) amp, which I like a whole lot better. Still, I have an MP3 player, which acts as an external hard drive and it's nice to be able to access all the music on the drive. If I'm really working hard and I just want to put together a long playlist, the computer setup is ideal. I'm not listening critically so the sound quality is fine.
As far as software goes, I primarily use foobar because it does not use too much of my computer's resources, which seem to be more and more taxed these days. I really like the Winamp visualizations but they sap all the juice out of my computer. QCD is also loaded on my computer but really foobar is my player of choice.