Thanks so much for the reply Cory- I had just started giving up hope...
The house is a very small very old house, constructed in 1927. There's pretty much no insulation at all. At the longest the cable extends to, the signal then has to pass through two rooms with no door or wall between them, and then a wall to the outdoor area. The shed is only about ten feet away from that wall, and a story below. The shed is made of wood. There is no doubt most houses have farther distances and more obstacles for their wireless signals to travel to- If I leave the current airport express where it is, it can get the signal (occasionally loses it) but it's a very slow connection, not quite dialup, I would say more like an internet cafe in India... If that helps. I have experimented with dragging the cable as far as it will go to the center of that room so it has a more direct route (sight line to the wall the shed is through) and the signal noticeably improves, though nothing like the having the computer in the room itself.
Even boosting the signal enough that it functions with quick speed on the internet, and I can download and upload files would work for my purposes. I plan to use it mainly as an edit station and not for browsing the internet, so just getting it to useable speed is all I need, and I'm open to any solution.
I thought of trying those airports only because I had them laying around, but whatever you think might be best let me know.
Again, really appreciate you following up, working in a rent-a-office space as we speak!
Austin