Multiple ip's on a single nic + web listner

Hi,

I'm trying to configure a web publishing rule and at the moment I'm using the exchange listener to access the site from the web.

Because I'm using the exchange listener, there's an issue with the ip address......So I want to create a listener specifically for the site I'm trying to get too and not the exchange listener.   I'd like to add another ipaddress (external), but this is where the waters get muddy!!  How do I add another ip address to the NIC?  If I go to the listener properties and select networks, there's only one external ip......how do I create another object and give it another ip so it appears in the "Selected networks for this listener"

Thanks in advance.