I'll try to explain as simply as I can, even though it is rather convoluted:
Two entities , a small office and a large office, that are in buildings across a parking lot from each other and have ethernet running between their two buildings. Currently, there is a Dlink NAT router between the two offices which allows access from one pc to the larger office. The large office has a host system that must see a unique IP from each host, or it won't allow a login. Their needs have changed recently and the small office now needs access for several pc's to this host system next door. The administrator for the large office wants the smaller office to install a Cisco dual ethernet, and to re-address their space. The small office doesn't want to re-address their space since they also have a couple of VPN's to other entities.
As a solution, could I just add a secondary ethernet address to the Cisco? If so, would I then add a second NIC (they all have Win2k Pro) to any pc that needs access to the host system at the large office? Or is there an easier way? The administrator from the large office has recommended setting up static NAT addressing on the Cisco, but I see that as more potentially more complicated.