Like Skip555 said... You're just extending the existing TCP/IP network to all three buildings. How you do it is all just site design / physical-layer. The DSL proper (modem, router) can remain in just the one location.
Now, a question (this being a church, and me being familiar with how those projects sometimes go...) -- Do you NEED internet at all three buildings?
Okay, sure, if you have a school/preschool, you need the classrooms and/or lab to be able to access the internet (as a computer lab or a library are usually a certification requirement). And the admin people need to access the internet for website updates, email, etc. -- but much of the campus probably doesn't need internet.
Case in point: I did some volunteer work for a church with a school and preschool. We set up a Peer-to-peer network in the admin area, and then we set up a lab in the same building for the school. Well, the principal wanted every classroom to have two computers, each with internet access. Me and a buddy spent our vacations that year running cables to 6 classrooms in 5 modular buildings, and adding hubs in three locations to achieve this goal.
Come to find out, the teachers were asking to *remove* computers (they tend to take space and to be a distraction) and just wanted students to use the lab during the designated "Computer" classes.
And it turned out that the "computer classes" consisted mainly of "keyboarding" (typing) and "how to look stuff up on the internet."
So the network we put together was serious overkill. Which brings me back to my point: Are you SURE that you NEED DSL at all three buildings? Because if there's not a plan and a purpose for it, it's overkill and you'd be better off using the time and resources elsewhere.
