[thayerg]

http://www.rogueamoeba.com/

has just released the windows version of Airfoil, which transmits any kind of pc audio to an Apple Airport Express. Price is $25. Using the Airport Express's toslink output you have a flexible and inexpensive way to enable pc audio without being locked into iTunes.

[Loftprojection]

That's a nice little software.  I never looked at the Airport Express because in my mind it was an Apple only type of equipment.  I checked it out at the same time as your Airfoil and it brings up some questions!  I wonder if someone ever compared the quality of the digital out in the Airport Express versus the Squeezebox?  

Thanks for pointing out this Airfoil, very interesting.