Internet Connection

I am stumped. I am visiting my father and his computer is connected through a DSL line. He has XP and only 1 Local Area Connection it goes through. Right now, only IE6 can access the internet. I downloaded Firefox but it can’t see a connection. The same thing when I downloaded IE7; it couldn’t detect an internet connection either. And no program I launch that needs internet access can detect a connection. I am an author with little technical experience, but this is the best forum I have found in giving easy to understand answers. Thanks for any help you can offer.

Tony