Connecting to 2 networks across a Wan

Hello all, here is my question and thanks in advance if
someone can help me out here.

We setup a Windows 2003 server with active directory and we named it headquarters.
This server is on LAN that has a T1 all behind a Netopia T1 router with a static IP.

Netpoia 4600 Series link http://www.netopia.com/equipment/routers/4600/index.html

Ok next setup is a Windows 2003 server on a LAN is located 250 miles away using a DSL line from SBC. We use the 2wire DSL Router provided by SBC. That network is bridge and allows us to user public static IP?s.

Now how can we setup our Networks so our satellite offices login into our main headquarters servers?

Is this possible?

Chris