Internet Connection Sharing

Networking beginner, have managed to create home network of 2 PC’s, 1 running 2000 Pro, one XP Pro. Network fine with Cat5 and TCP/IP addressing. Want to share Dial-up modem on Win2000 machine with XP machine: have managed to get settings OK so that Dial-up and LAN work on host (2000) machine, but can’t configure ICS without losing network setup…i.e., if network configured for ICS, this removes fixed TCP/IP address from client, so it drops off network…Very basic question, am reading it up, but any quick tips appreciated.