So, you pulled the network card and installed a new one but you didn't uninstall the driver for the old one first and now XP (or W2K) is telling you there is a hidden NIC and if you use the same IP it might cause problems.

Well you can get rid of it if you edit the registry.

First thing to do is assign a different IP address (statically) to the card you have installed now, pick one that wasn't on the machine before.

Ok now open regedit and go look at these keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces

there you will find entries for all defined network cards, you should be able to see which is current by looking for the IP you just assigned it. Don't delete that one but you can delete the others if you don't need them.

Then go up a couple levels to:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services

and at the top of that list should be the same GUID's you just saw, again you can identify them by IP address and delete the garbage.

Ok, that's it. Reboot for good measure then setup your current card however you want it.