Windows XP Internet Connection Sharing LAN+WiFi

I have a DSL box with only one physical port, it has no router functionality.

One network cable comes out from the box and gives me an IP address through its DHCP server. (192.168.0.2 it gives my computer). I want to share this connection with my friend over wifi that we both have on our laptops.

IOW – Internet comes in from the DSL box into my Ethernet card in the laptop. If I try to start InternetConnectionSharing on that connection in WindowsXP it tries to change the IP address of the Ethernet card – which will ruin my internet connection. HOW IS THIS POSSIBLE TO ESTABLISH???