Linux Server OS for Media Server

What's a good Linux Server OS distro to have for a Media file server? Me and my friend have set up CentOS server to practice for our IT knowledge/careers since it is so similar to RHCE. However, I'm not sure if that's what I want to use for a media server. What other distros would be good for storing media files and streaming them with ease? The server will be streaming to XBMC boxes, Windows machines and an Apple TV. It would be nice to make it universal and easy to stream to Windows machines, MACs and Linux machines.