I wasn’t able to use my Western Digital drive on my Mac, although it reads the files on my drive but it does not allow me to modify them or add additional files! and thus the only possible way to make this happens is to format my external drive! Meanwhile I am formatting my Passport to fat32 in order to use it with both Mac & Windows OS! I might face one problem though! with fat32 there is a limitation of size! I wont be able to load a file sized larger than 4GB which is not really a big deal!