WD My Book World Edition + AirPort Express + iTunes. Will it work?

Hi
New to this and would love to know if someone can help me with my question!

At the moment, my vista laptop connects wireless to my AirPort Express which is connected straight into my hi-fi (which is downstairs) which i use to play music through iTunes.

My hard drive is at bursting point and the Western Digital My Book World Edition has caught my eye as it looks like a good way of getting 1TB of storage without going through the hassle of replacing my laptop HD.

so basically my question is this. Can I connect the WD My Book World Edition straight into my wireless router (which is upstairs. I can’t move it as it’s connected to the only working phone line), move my iTunes library across to the WD My Book World Edition and still access my iTunes wireless through my laptop to play through my Airport Express?

Hope that makes sense and would appreciate any feedback!
Thanks!

I have no experience with AirPort stuff, but I use iTunes with MBWE (which uses firefly daemon as iTunes server) and MBWE shows up as a shared device in iTunes “Shared” pane.