Please help, Macbook networking problem

Here is the problem, my macbook will NOT connect to the internet, but IS connected to my home network, which is NOT broken. My iMac which connects to my network over wifi works just fine. MY macbook which connects to the network over wifi does not work. My network settings are telling me that Airport has no ip address. So i plugged in my ethernet cable and it still says it has no ip address. The status says "Unknown State." It is not the ethernet cable or ethernet jack because those are what i use to connect my xbox 360 to xbox live. I have reset both my modem and router. Still nothing. I can connect to the other computers on my network and move files between them, but i can not connect to the internet.