Terryaki

hi i recently just bought a my book world edition 1tb, i originally had it set up at a friends house running 32 bit vista my friend had done all the configuring cause i dont know a whole lot about networks. at his house he has the same basic set up as i do here he has his desktop attached to a cable modem and he has a linksys wrt54g wireless router and the way we had it was i was wirelessly conected to his router with my laptop and the hard drive was connected to my laptop via ethernet port. i used the drive to back up all my media files then afterwards he reformatted my laptop and installed windows 7, i ran all the updates and installed what was needed. So after this i brought it home to my place the only difference between our network set up is that i use a dsl modem rather than a cable one. when i plug in the drive it comes up in the network center as an unidentified network, it says its a public network "connections: local area connection" the local area network says it has no internet access i ran a diagnosis and it says that local area connection doesnt have a valid IP configuration. could someone please help me fix some of these issues?