Broke my company's network, how do I get it set back up?

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http://serverfault.com – My dad moved his office. The new location will only have WiFi access, but he still needs his server setup and the other machines connected to it. The server (don't laugh) is an old Windows NT 4.0. Then I'm trying to connect just a standard Dell desktop to it (running Windows XP). The old location had a broadband network. When I'm on the server, I can't connect to the DHCP. Since there's no internet access (and a server to connect to via Broadband connection), how do I set the ip address for the server. IP config says no ip address for the server (obviously). I've googled a bunch for "configu (HowTos)