Have you looked at the Dolby Labs website? (Dolby Home Theater Speaker Guide) It is really helpful as to to speaker positioning. You will see that the ideal solution is to have a listening position forward of the back wall, with the surround speakers at about 4 o'clock and 8 o'clock. Personally, I think that a bit of height (therefore wall brackets not stands) makes the surround effects more believeable and less 'in your face'.