Sure, but need a little more info.
I will assume that you already checked the cable and router LAN port since you do your own builds.
Windows 7, which version Home/Pro/other? Does the LAN adapter show up in the device manager and say that it is working properly? If you look into the network control panel is the network unidentified? And if you type ipconfig into the command prompt box do you get a real LAN address or a 169.x.x.x address?