I have one too and my G4 Cube and airport base station sends music to it from iTunes. I often stream cooljazz.com to the express and then into the Ht system. Great music before a show starts!
Apple Airport Express Very Cool Product
Just wanted to share my experience with this product. I have become a big fan of my iPod and using iTunes and just received my Airport express and it is awesome! Setup was not exactly as easy as you would think but I finally figured it out. The Sound Quality is similair to the iPod but the mult-room and flexibility of this is worth the sacrafice! Anyway, if you are using itunes check it out..
Chris
Chris