Set up and Use Internet Connection Sharing

With Internet Connection Sharing (ICS) in Windows XP, you can connect one computer to the Internet, then share the Internet service with several computers on your home or small office network. The Network Setup Wizard in Windows XP Professional will automatically provide all of the network settings you need to share one Internet connection with all the computers in your network. Each computer can use programs such as Internet Explorer and Outlook Express as if they were directly connected to the Internet.
You should not use this feature in an existing network with Windows 2000 Server domain controllers, DNS servers, gateways, DHCP servers, or systems configured for static IP addresses