Well, I just had exams, which means I had a lot of spare time, and during that spare time I noticed that many games don't support a Windowed Mode.
I hope D2: ED will support windowed mode. I tend to just open MSN and then start one of my games in windowed mode so I can keep in touch with friends while enjoying my game, yet some of my favourite games don't support windowed mode so I just play other ones instead. I know there exist professional in-game chat programs for that(I use X-fire for this purpose) but a lot of my friends aren't gamers and just log in once in a while to say hello.
I don't know why some games don't support windowed mode, is it hard to code it in?