I have an older Airport Extreme, 2009, and I want to extend my wifi network to another part of my house. I'm ready to run the ethernet cable but I'm not sure what I would be better off doing. I was planning on getting an Airport Express and putting that downstairs (the Extreme is upstairs near my office). But would I be better off buying the new Extreme and using the old one to extend the network? I do have a 2013 Macbook Air, but that would be the only device taking advantage of the new wifi ac.