sean,
don't even bother, its simply not worth it.
But, as Mark Twain said
'only dead men are allowed to tell the truth in this world.'
And here it is, from the grave.
http://video.google.co.uk/videoplay?docid=-3281135121622917423&q=frank+demartini Frank DeMartini, head manager of the WTC construction team, talking about how the towers were deliberately built to withstand the full impact of a fully loaded 707 commercial airliner.
He goes on to say that the buildings were so well engineered that they could easily take 'Multiple' impacts and stand.
That unusual outer structure of the towers, crosshatch style outer frame was designed to spread the load of the impact horizontally and vertically across the surface, disintegrating any plane into millions of tiny parts.
There's no way two random collisions in two random areas could bring down those buildings so uni-formly and in the same time frame, at the same drop rate (near free fall).
PS the difference between a 707 and a 757, is very minimal , wingspan a few feet less, weight about 10-20 tens less.