Windows 2003

A – I have Windows 2000 Server without AD but DHCP. This computer is using 200.201.1.??/ 255.255.255.0 series of ip address connected to a DSL modem using 200.201.1.250 ip address.

B – I have installed Windows 2003 with AD using 10.30.1.?? / 255.255.255.0 addresses. Due to various reasons I want to move my all users from A to B manually. I have Two NIC and want to configure network B to access internet through A for couple of days untill I move all users to the new network. I have tried to configure Windows 2003 as router, NAT, also bringing the network but no sucess. Please help me to configur the network.