Pre-existing Windows 2003 network and those who love wireless

I have a new network that is running Windows 2003 Server with Active Directory inside our corporate office with wireless Linksys routers with a T-1 line. I have 29 other locations that have either dialup or DSL connections also with a Linksys wireless router. Each router has a separate IP address assigned by the ISP we use. I have to get all location onto the one domain but because we use Active Directory I am afraid that will cause an issue. Any ideas on how to connect all of these locations to the main office?