If you ever get a chance to watch the HBO movie "Tailspin" you should. It is the best explaination of what happened that I've ever seen.
And Grun... knowing that it's a 747 isn't the same as knowing that its full of people. Most of our support planes (the C-135s and E-3s) are based on the Boing 707 airframe. The P-3 is based on the lockheed l.188 Electra airframe. Most if not all modern airforces use civilian airframes in such a manner. A 747 packed to the gills with electronic collection and telemetry equiptment would be some scary ****.
It certainly should not have gone down the way it did, but in the end it was nothing more than a tragic accident. There are claims on both sides of intentional misconduct. That the plane was known to be full of passengers (and presumably the russians shot it down just to hear their screams) and the Russians counter with **** like the pilot was working for the US government to test Soviet response times, and to elicit priceless inteligence on Soviet interception techniques. Personally I don't believe any of it. We fly intel missions in the area all the time. They react to them, we give them the finger. It was the natural order of things at the time. It doesn't take much to go over the edge when you ride it for too long.
-Sik