I am amazed at the stupidity of many on this site regarding speaker height.
Surround sound speakers should be about 2 feet above head height, with the centre speaker being at head height. This allows the user to not be distracted by the surround speakers when voices are coming out of the centre speaker. For big rooms the surrounds should be higher with regards to head height.
Stereo speakers should be at head height or preferably above the head aiming down on it (more coverage however creates dead spots under the speaker)as you are trying to get listeners to hear your great sound.
... and subs go on the floor as their sound spreads more (wider) then higher frequencies (rocket science).
Hope this helps all the idiots that argue about this. If you think I am incorrect, feel free to debate.