DHCP relay is configured via the Routing and Remote Access Snap in.
From the Administrative Tools menu on a Windows 2000 Server, open the Routing and Remote Access tool. Expand the server icon, then click IP Routing (you may have to right-click the server and choose Configure and Enable Routing and Remote Access in order to expand the server icon). Right-click the General Tab, then click New Routing Protocol. In the New Routing Protocol box, choose DHCP Routing Agent, and click OK. Open the Properties for the new DHCP Relay Agent and fill in the IP Address of the DHCP server, then click Add.
Remember, the machine must physically be located on the edge of both subnets (i.e it must have more than one NIC).