A lot of DSL modems actually have routing functionality that interferes with your actual router. They tend to use a PPOE setup, which means you have to tell your modem to not do PPOE and use the settings that it had to tell your router it's a PPOE connection, complete with the login user/pass and external IP address the modem was getting. I know that sounds complex, so maybe just google on that subject with some keywords and you'll likely find the steps for it.
http://www.cnn.com/2004/TECH/space/09/02/space.signals.reut/index.html Wow, I'm not even sure what to say about this one. It will most likely turn out to be nothing, but even so, this could be something potentially amazing.