When you want to transfer non Amazon paid for books from your PC to N7 I found the best way is to email the book file to your kindle.com email address and it is then stored in you Amazon archive file. You are then able to have it transferred to your android device ( needs to be registered in manage your kindle) which is done automatically or using your kindle app on N7 sync from the menu and the file downloads. Hope this helps.. Also your books can't get lost as they are always stored on your Amazon archive.