New K8,nForce4, nVidia NIC: Won't acquire IP address

[NewPC]

Computer arrived this morning from MIS. Runs like a top, but will not acquire a valid IP address even though it detects the modem and, when we connect it to our home network, it will detect shared files.
Tried: ipconfig/release and renew, reinstall driver from CD, contacted internet provider {says NIC is bad}
Any suggestions, anyone? I really don't want to ship it back.

Thanks.