Active Directory over the Internet

I am interested in setting up Active Directory to work over the internet. What I mean is that I have a domain controller in one location and I want PCs in other locations to access it. Here is what I have currently

Location One: (Datacenter) -
1 - Windows 2003 SP1 server setup with AD as the DC and DNS
1 - Windows 2003 SP1 server setup as a web server
1- Windows 2003 SP1 server setup as a development server

The 3 servers are joined by a router/firewall and all connected to the domain. I can access all servers with multiple static ips mapped to internal ips. The servers are working great and can pull all the information I need.

Multiple Locations: (Satellite Offices) -
I have multiple little satellite offices with one or two computers and I want to join them to the domain. All have broadband internet connections.

I have researched a lot and looked at the Windows 2003 R2 with ADFS as a possible option. Seeing that this a small operation I am curious if that is what I need to do. Is there a better method for what I want to accomplish?

I can get my way around networking pretty good, but this is a little above my head. What I am looking for are some steps to take to get my remote computers to join the domain I have setup in the datacenter. I appreciate any assistance you can provide and if I have neglected to provide any vital information please let me know and I will be happy to respond with it. Thank you for your time in advance.

Best regards,
bzappdev