Help setting up Airport Exposes

I'm not 100% sure I have understood your question, so forgive me if this answer misses the mark. You will need an operating computer in the process. The external drive can be the storage container but it will not run an operating system (OS). I have three AEs connected to different systems and use an old surplus PC with Win7 and iTunes to stream the music I have stored on a network drive. An internal or external USB would do as well. I then use an iPad with the "Remote" app to control iTunes on the aforementioned PC. Works like a charm and allows me to turn the different AEs on/off and contol volume individually as well.

Glad my answer was on point! As far as the PC goes, you can get away with a really basic low end machine--all you need to be able to run is the OS (windows) and iTunes. iTunes isn't very intensive at all and I think you could probably get the netbook to work fine. Otherwise and old surplus PC ought to do just fine.