xbox live dns failed

I am trying to connect from my PC to my xbox via an ethernet cable (straight through I do belive). I use a wireless card to get my internet, so I used my normal nic card to run the cable from my computer to the xbox. It says the cables are detected, the IP address is found fine, but it fails at the dns stage (as in it cannot detect it). I'm sure that internet connection sharing is enabled, my software and router firewalls are properly configured. Yet I cannot seem to find the source of my problem.

Anyone have a solution?

Thanks,
Axis304
:major