Just share the external USB drive and you're all set. Windows sees it as a local disk no different from your main hard drive and shares it the same way.
Correct me if I am wrong but to do what you are suggesting would mean connecting the usb drive to my windows pc and then sharing it. That means I'd have to leave my pc on everytime I wanted to access a file from it. I don't really want to do that.
What I want is the ability to transfer files onto an external drive via drag and drop in windows and then be able to access it on the neuros. I figured having a networked drive independent of any pc would be the best way of doing it.
I thought the LaCie drive would be picked up easily as a network drive by the neuros - what are the potential problems? why might it not work?