I currently have my 1TB External Hard Drive for Time Machine hooked up locally to my iMac. I was thinking of freeing up a USB port by connecting it to my Apple Airport Extreme. When I searched about this I saw posts from a year or so ago that Time Machine would have to start over since it archives differently connected to Airport Extreme vs locally. Is this accurate? Should I just by a USB hub to give myself more ports or hook up the extra external drive for additional memory(like iTunes and iPhoto overflow) to the Airport Extreme?