If you have setup DHCP on the server, it can be done. The clients will have
to set to obtain an IP automatically from the DHCP-server, which will also
push WINS and DNS.
Unfortunately you will have to hit the desktops one more
time and change their settings to use dhcp and dynamic
DNS.
On the server under dhcp you can configure all pertinent
info such as DNS, Gateway, WINS, etc. This is under
server options. At least the next time you make changes
you will not have to hit all clients.