I am currently experiencing problems using a WINS server to provide netbios names for clients on a Cisco WAN using NAT. The WINS registration is using the Inside Local IP address, in this case a 172.16.x.x address. NAT is translating the IP address of the packet in the IP header but seems to be ignoring the Netbios datagram header. I can ping the translated address in this case a 195.106.x.x address after checking the NAT translation table so I know the NAT is translating properly. The routers in question are 2500 series routers connected to a 3640.
The topic of this forum is Wireless Mobility however there are a number of professionals online who may be able to assist you. We are always considering additional forums for such topics and I will make a note of your post.
You can use a local LMHOSTS file to over-ride WINS resolution or better yet statically configure BOTH the natted and non-natted IP address in your WINS server. If you have your WAN users VPN to your network and bypass the NAT altogether, you wont have to deal with all this. Your Cisco design engineers should be able to give you some more workarounds.