You sure the wireless in the new laptop is good does it work perfectly elswhere? I mean why tottaly reconfigure the airport extream if everything else is working correctly..? Have you tried connecting to just the extender and the aireport extreams wireless? Does the cablemodem have its own wireless you could try? And last one but have you tried hardwire to make sure everything works as it should? Oh can you ping one of your media devices? Sounds like a DNS issue to me. See if you can ping yahoo.com if nothing try to ping yahoo by it's ip if that works then DNS issue..