Well, that's the difference between world and essential edition.
BUT, I have now had my ethernet WD up for 2 days without any kind of trouble. Just wanted to say that. I am now running 7.10b4, my last try was with the 7.04. I do not know why, but my previous problems are gone :-). I have played movies from it (but just short bits) and transfered about 200GB to it and it has never disappeared from the network.
My SPDIF is even working so now, so I finally have the opportunity to use this great system!!