Window XP supports Windows Internet Connection Sharing (ICS). This does not eliminate the need for a home gateway. Using ICS requires that you dedicate one computer to act as the "connection sharing" computer for your home network. This computer must be left on and connected to the Internet at all times for other computers in the home to have access.
Running ICS consumes valuable resources on the connection sharing computer and any interruption in its operating system or networking software will cause all computers on the home network to lose Internet access.
Using ICS requires the use of several different network adapters on the central computer, one for the Internet connection and one for each of the desired network technologies (HomePNA, wireless, Ethernet, etc.). The 2Wire Gateway is a specialized firewall gateway that is designed to efficiently and securely manage a home network.