I had a regular winblows xp laptop, and purchased a seagate external HD. I saved all my files, music, and pictures on it and then I eventually purchased a new iMac. I plugged in the external on the iMac and it showed up on dashboard, but then unplugged it because I wanted to save some more things from the windows machine. I tried plugging it in to the windows and it was unable to read it saying that it needed to be reformated, so in a panic I plugged it back into the iMac to try and save it, but the iMac also doesn't regnonize it. I can ignore it and nothing happens, close the window, or initialize it, which I believe will reformat the HD. Please give me any help because I have lots of valuable pictures and files on that external that I need.