i have a TB external HD and was wondering if that can be used with time machine to back up my mac? also i have some other things on there (other stored files), would the time machine erase those, or would it remain untouched? ALSO, i have itunes media folder already stored on the external HD (as in the source folder is on the external HD) to take up less space on my main HD, will it make a back up again of my itunes media folder? anyway to tell it not to? since it would be redundant and waste space on the external HD. THANKYOU!