I'm planning on purchasing the new MacBook - this will be my first mac. I recently bought an external hard drive for my PC but it is windows/mac compatible. I've put all my audio/photoshop files on it...will these files transfer well if I plug my external hard drive in my mac or will the mac need to format the hard drive? I'm hoping to use this hard drive as a huge flash drive type device. I would hate to plug in my external hd into my new mac and lose all of my PC backup files! Let me know!