When migrating from Windows SBS 2003 to Windows SBS 2008, you may find the same problem I encountered this morning if your using (Routing and Remotte access Services (RRAS) on your old Windows SBS 2003 server.

It will complain that your destination server IP cannot be the same as your Gateway server address during the installation of Windows SBS 20008.

to fix this:

1. Go to start then run and type
   control netconnections
   
2. Right-click on the local area network connection you use for the internal LAN.
3. Click properties.
4. Click Internet Protocol TCPIP then click properties.
5. Click advanced.
6. Under IP addresses, click add.
7. Type your new IP and subnet

This isn’t enough.
You could in theory specify to the installation of SBS 2008 that it should now use the updated server IP that you’ve just added so that you don’t have to go changing your RRAS config but unfortunately the wizzard will complain that your domain cannot be contacted.

So, you’ll need to update RRAS to use the new IP and then specify this IP as the gateway in the setup wizzard.

It’s fun isn’t it?