I'm currently using a Windows PC and I'm thinking about buying a Mac in a few months--my first Mac ever, actually so I have this kinda dumb question that I'm hoping somebody here can answer me. I have a WD My Passport external HDD (1 TB) that it's compatible with Mac software (it says so in the box) but I hear that in order to use it with Mac I'll have to 'reformat' it (not sure what's the English word for this, sorry) but my question is: do I have to 'reformat' it even to read the files that are inside or that's just necessary if I want to store new files in it? In conclusion: if I have this external HDD almost full of different files (music, movies, Word documents, etc.) will I be able to use them/copy them from my Mac even tho the HDD is formated for Windows? Thanks a lot in advance.