Tipp: How to configure a first gen Airport Express under El Capitan (10.9) or Mavericks (10.8)
With the latest update of the Airport Utility to 6.x the old Airport Express is no longer supported. At the same time, it is no longer possible to use the 5.x version under Mavericks or El Capitan, which could mean that you're stuck if you like to setup an old Airport Express, as I had to this week. Also, the Airport Utility on iOS does not support this hardware.
Luckily, there are helpful folks out there. Under http://coreyjmahler.com/2013/10/24/airport-utility-5-6-1-on-os-x-10-9-mavericks/ you can find a little piece of software that re-enables the use of 5.x under the current MacOS versions.
This saved me a lot of time, and hopefully, to some of you as well.