Happens a lot with XP's network wizard.
1. Go to Control Panel | Network and:
a. Set the workgroup name to home.
b. Enable File and Printer Sharing.
c. Install Client for Microsoft Networks.
d. Install TCP/IP and configure it as follows:
IP Address: Obtain an IP address automatically
WINS Configuration: Use DHCP for WINS Resolution
Gateway: remove all gateways
DNS Configuration: Disable DNS
2. Go to Control Panel | Internet Options | Connections and:
a. configure it to never dial a connection.
b. click the LAN Settings button and un-check all of the options