In this case, the fault isn't apple's, it's dlink. There should be a way to see what the hex password is for the wep network
Realistically tho, wep is awful, and if you can, you shoudl upgrade to a wpa capable router. And for the most part, wpa jsut works for almost everything.
My setup is pretty close to it just works at this point, tho there are still some quirks to how the output files turn out. I use handbrake universal setting, and I've been pretty happy. The kids are able to use the apple tv to watch their movies upstairs, which I can control with my iphone from anywhere in the house, and we can watch a LOT of variety of things using plex on the mac mini on the main tv.