Windows Server 2008 dual nic trouble

Hi all,

First of all let me explain the situation:

Currently I've got a server running Windows Server 2003 SBS. It is configured as a domain controller, has two NICs and has some filesharing. Nothing too complicated.
NIC 1 is the NIC to the internet, NIC 2 is the NIC to the 5 (XP Pro) clients. All clients log in with their name onto the domain. They get internet access and access to the shared files through the server.

The new configuration will be about the same. There will be one server with two NICs, one for internet, the other for the clients through a switch. The clients need to log in through the domain and have full internet access, just like in 2003 SBS now.

But I can not get this configured, trying for more than a week, installing all kinds of roles and services without any success. So I reinstalled to try it again, currently there are no roles installed. NIC 1 has a static IP, NIC 2 is not configured yet (as in: it is set to DHCP and connected to a swtich, which is connected to one of the clients for testing). I'll configure the domain later, after everything works.

I tried bridge the connections, it worked, but the clients got a wrong IP and could just log in (they should only be able to log in through the domain). On the other hand when they could log in to the domain they had no internet access, and I need both. I followed numerous tutorials with no success. Installed DHCP, NAT (through routing & remote access), put the NICs into RIP, nothing, nothing helps.
So here I am with an unconfigured Windows Server 2008 Standard x64. Could anybody help me out?

This is how it is:

INTERNET --> Router --> Server NIC 1 (static IP 192.168.1.200)
Server NIC 2 --> Switch --> Clients

The router needs to be there as there are more computers to be connected to the internet, but not to/through the server.

In 2003 SBS this was a 10 minute job and still works fine, but the server needs replacement. Thanks in advance