Well, an IPCONFIG /ALL run on any machine will list, among other things, the WINS servers it is configured to use. So, if physically going to each machine is not possible, then you can try PSEXEC from www.sysinternals.com
PSEXEC will open a Command Prompt on a REMOTE system. You can use it to connect to each target machine, then run the IPCONFIG /ALL and see what each target says.
As for changing WINS settings, it depends on how your clients get the WINS setting. If your DHCP server (if you run one) sends out the WINS setting to clients, then just change it there to a new WINS server IP address. Then when clients refresh IP addresses, they get the new address.
If your clients have static IP addresses, then you can use NETSH from the Windows Resource Kit to change the WINS address from the Command Prompt. And, since you are already running PSEXEC to connect to your clients, that is how you could do it. Connect to each target using PSEXEC, then in the open remote Command PRompt, run NETSH and change the WINS address.
hope this helps