I'm thinking of upgrading my 5.1 to 7.1, but I'm still not quite sure how they generate the sound for the 2 extra speakers (surround left and surround right), since all DVDs are just encoded in 5.1 only as far as I know. Do they just mix the front left with rear left to generate the surround left, front right with rear right to generate surround right? Also, where should I put the two extra speakers? I have seen quite different layouts, let me draw it below: Layout 1: FL TV FR SL SR RL Viewer RR Layout 2: FL TV FR SL RL Viewer RR SR Looks to me layout1 makes more sense, because in layout2 the 4 speakers are almost in the same plane. But without knowing how they generate the 2 extra speaker sound in the first place, I can't really make a good judgement. BTW, will HD DVD or Blu-ray have true 7.1 effect? Lots of questions in this thread, thanks in advance!