I learned on another thread that I technically can't use Time Machine to back up to a non-Apple external hard drive (Western Digital) that is connected to my airport express by a usb cable. Does anyone know whether I can safely use the drive for other purposes? I.e., can I safely store my iPhoto and iTunes libraries on the WD Drive? Or does airport express not support any external drive other than a Time Capsule? Does the Time Capsule work as a full external hard drive, or does it only do Time Machine backups?