I have an external hard drive that was used for storing pictures when I was using Windows XP. I can move pictures from this external hard drive to my MAC desk top but cannot move pictures from the desktop back to the hard drive. Is this because it was formatted for Windows and if so once I have backed up my external hard drive how do I reformat it so it can be used with my MAC? If this is not the case than how do I move files from the MAC to the external hard drive? I am becoming very frustrated and am wondering if I made a mistake in moving to Apple.