Yes and No, and yes I know that this has been answered, but I guess it deserves a simpler explanation for people like me for both my Yes and No.
There are three doors, you choose 1, there is a 1/3rd Chance of you being right.
Lets say door 1 has the car and doors 2 and 3 have goats.
Scenario 1: You chose 1
The presenter will open one of the leftover doors (either 2 or 3) with the goat and ask if you would like to switch, if you switch, you will lose
Scenario 2: You chose 2
The presenter will not open door 1 he will open door 3, in this case if you switch you will win
Scenario 3: You chose 3
The presenter will not open door 1 he will open door 2, in this case if you switch you will win
Given that the original probability was 1/3 and after the door opening, the odds of winning with a switch is 2/3, you are better off switching.
This, however is the logical answer, then there is the philosophy, if you had a reason to choose door 1 and you believe that reason has not changed, you should not switch, because in life, being wrong about chance is ok, but not sticking to your decision is a bigger problem :) than losing a sports car