The Game Show Paradox

I am a contestant on a game show. The host of the show presents me with a choice of three doors; 1, 2, and 3. I don't know what is behind each door, but I do know that behind two of the doors are beat up 1987 Hyundai Excels, and behind one of the doors is a brand new Cadillac Escalade.

The cars were placed randomly behind the doors before the show, and the host knows which car is where. The way the game is played out is as follows. The host lets me choose a door. I choose door #1.

Before the door #1 opens to let me see what I've chosen, he opens one of the remaining doors, say door #3, to reveal a Hyundai Excel (he will always open one of the remaining doors that has the booby prize), and asks me whether or not I want to change my choice to door #2. What should I do? I want the Escalade!