config DHCP and WINS for roaming user

We have three offices. The main office has a NT server acting as PDC(192.1.1.x) while the other two(192.1.2.x, 192.1.3.x) each has a NT server acting as BDC. All NTs are in the same domain.

Each NT server are configed with DHCP, WINS, RAS, DNS services. All clients uses DHCP and each DHCP has only one scope configured with local WINS and DNS.

We have sales people using laptop to connect to ethernet LAN. They could be at main office in the morning and in the other offices in the afternoon. What they have to do now is run ‘winipcfg and release IP’ each time.

What is the best way to config DHCP(renew time) and WINS (pull/push) in this situation? Any recommendations?