He'll have that anyway, as both routers can run as WAP's independently of whether they are DHCP servers. It was the two DHCP scopes and servers I was querying....as a wireless client on the second (non-routing) router will simply pass the DHCP request back up the ethernet to the main router running the DHCP server and the ADSL WAN connection.
(Plus, most routers when you turn on WPA2 and WEP don't allow you to enter WEP Key 1, which screws up a NDS as that's the only key you can use, so he'll need two WAP's unless he's going to back the Vista client off to WEP as well.)

