Windows 2000 SBS and remote Win 2003

We are running Windows 2000 SBS in our office + a Citrix server and I need to configure a new Windows 2003 member server with SQL for another remote branch.
There will be only 4 people in the remote office. They have a static IP address and have broadband internet access.

How would remote users authenticate to Windows 2003 server if their server is setup only as a member server? There is no WAN connection between the two offices.
I understand that with Windows 2000 SBS you can have only one DC and any other servers have to be a member server.

Please share your thoughts.

Thanks
Al