Let me make sure I understand this: You are comparing Microsost Flight Simulator to real life? You are joking, right? I am almost speechless...

Well, to try and maybe answer your question (which would be more appropriate for the Washington forum, BTW), lots of times when you start a flight sim all of the traffic from the past hour or so goes to the runway at once, not taking into account real time. I believe DCA typically only uses one runway at a time for takeoff. Wow, I feel like I am on airliners.net, so will stop while I am not losing...