Nope, the odds that you pick the right door in the beginning are always 33%. It took me a while to understand this too. There are three possible outcomes: (1) You pick the right door in the beginning. You are then shown one of the wrong doors. If you switch you lose. (2) You first choose wrong door A. You are then shown wrong door B. If you switch you get the car. (3) You first choose wrong door B. You are then shown wrong door A. If you switch you get the car.
If you switch, there are two outcomes that result in you winning the car. The only way you lose if you switch is if you chose the correct door in the first place, but the chance of that happening is only 33%, so if you switch you have a 66% chance of winning.
I became obsessed with this after watching the movie "21" it took me a while to understand it....
here is a simulator http://people.hofstr...ntyHallSim.html i did 50 trials of each method. when staying with my original door i had a success rate of 0.4 (20 out of 50) when taking the switch i had a success rate of 0.68 (34 out of 50)