Late to the conversation, but for those that asked about converting from FLAC to mp3, there is a program called foobar2000 (it is a winamp style player) that allows you to do this from a GUI interface. I did this for a boatload of FLACs - open in a window, select all right click, choose convert to mp3, select the quality and then let it run all night. Slick as heck.

I have 2 squeezeboxes, feed them FLACs and use low bitrate mp3s for the car. Am a huge fan of the system.