Two or more IP addresses can be assigned in windows using only one ethernet card. Using Windows XP, go to Start Menu –> Control Panel –> Network Connections –> Select the local area connection you want to assign two IP addresses.

Go to Properties –> Internet Protocol (TCP/IP) –> Advanced –> In IP settings, click add and add the IP address and netmask you want to give to your windows.

Now you can access your system using both the IP addresses.