I'm planning on getting either a new iMac or a rMPB soon. I would like to keep my iTunes library and photo library on a connected external USB drive. If I also back up my main internal hard drive to a second external USB drive used exclusively for Time Machine, the question that I have is, will Time Machine back up my iTunes and photo libraries on the external drive when it makes a backup? Sorry for the newb question, but I've never owned a Mac before. Thanks!