That's only part of it. A hub can only communicate with on 'puter at a time, so while one is sending/recieve, the rest are suspended. A switch will allow for simultaneous communication for all machines plugged to it. Your DSL line has a maximum bandwidth in it. If you put a router on it, it will just enable you to share your bandwidth with whomever else you plug into it. You do still share the bandwidth if more than one person is using it at the same time.