1. A system for selecting a delivery site, located on a distributed computer network, from which to a receive a file, the system comprising: a communications network; at least one content provider connected to the network, wherein the content provider stores at least one file; at least two delivery sites connected to the network, wherein each delivery site stores the same file as the content provider; a user terminal connected to the network; a network testing apparatus for testing the network and selecting a preferred delivery site from all delivery sites connected to the network; and a downloading apparatus for downloading the file from the preferred delivery site to the user terminal.