It depends on the wireless router you have, but refer to the documentation on how to enable DHCP on the wireless router. This way, the assignment of IP addresses should be handled by the router when the desktop or laptop machines connect to it. Otherwise you will have to statically assign private IP addresses to the wireless cards on each box, 192.168.0.10 and 192.168.0.11 for example.
Also if you have Windows Service Pack 2 installed, you might be receiving the error erroneously. There is a patch available here that might remedy some problems.
If this is also being configured in shared living/working domains like apartment buildings, obtaining a decent signal from the router may be a problem due to too many signal conflicts. When you view the available wireless networks on the machine, there should only be a list of your wireless connection to ensure that conflicts aren't occurring.
This was first published in March 2005