I have my boxee box connected via LAN to my HP ProCurve switch. I also have my Airport Extreme connected to that switch. While I can access the internal hard drive from the MacMini that is also connected to the HP switch, I can not access the USB hard drives that are connected to the Airport Extreme. I can connect to this USB hard drives from my MacBook Pro, no problem there.
P.S. I checked identify with account on the airport extreme. There is also no option to have no password.