Chris I don't think the forum is set up to do what you are after until after you break down into a category... then you can default by date. Unless I've missed something or misunderstood your question.
what i mean is this (btw, i think you got what i meant). when i go to the general discussion section, by default it shows by "thread title" in "ascending" order. i want to make it "post time", in "descending order". that way it shows the last post up top, just like the other sections. i always set it to that mode when i go in, but it would be nice if it was that way automatically.