the 512 figure you quote for your connection is the absolute maximum you could get on your connection and does not reflect what you WILL actually get, there are many deciding factors that can affect performence one in particular being your location ,age and condition of the phone supply cable coming to your property and also the quality and positioning of cables in your home,where possible keep them away from electrical cables and equipment.personally i see not much point in going for a 512kb package as the price difference is not that great on a 2mb package.