Computersweeper: Where (Major City, State) are you located and who is your ISP? I've never had a problem with the new BN Fileforum server in the Central US, though the SecurityWonks servers tend to be heavily loaded and the SaferNetworking servers are in Europe. It sounds to me like on top of the server issues you're having network issues, as most such reports have disappeared since the servers were re-worked a couple weeks ago.
Frankenstien: Once you've selected a server that usually works well for you in the Update Servers pull-down list, right-click the server name (not in the list, on the menu bar) and click 'Set this server as the preferred download location'. This server should become the default until you come back and either click 'clear preferred mirror setting' or pick a different one.
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OK, md usa spybot fan wins the race this time. We're now neck and neck at one tromped on post apiece. His is easier to read, but I answered two questions in one post. So there!