So you have two different internal NICs both with the same IP (192.168.0.1)? I wouldn't recommend this approach really. Is there any particular reason why say the second internal NIC couldn't be 192.168.1.1?
What version of Windows are you using?! Are you saying that the because the clients machines are off Windows (Media Sense) has disabled the interface; so that when WinGate starts Windows has hidden it, and thus we don't bind to it?! If this is the case, then we obviously can't bind to something that we can't see. The best way to get around this is to either, set each WinGate service to 'Bind to any interface' under the Bindings tab of each services properties. This does have the down side of being a slight security issue as this will allow external connections in. However, as long as you dont put a hole in the Firewall (assuming your using the WinGate ENS) for these services you should still be protected.
You can also disable Media Sense which should alleviate the need for performing the above. This is the link for how to do it for Win 2000.
http://support.microsoft.com/default.aspx?scid=kb;en-us;239924&Product=win2000
Regards
Neil