I'm kind of late to the digital music scene and am trying to organize my music on my pc. I'm using iTunes to import and organize my cd's as .mp3 files and using DoubleTwist to sync to our EVO's. We have some music on our pc purchased through iTunes as .m4a files. Are the .m4a files usable on other, non-Apple, devices? Is it worth the while, or even necessary, to convert to .mp3's? Any advice would be most appreciated.