Setting Random X Position from array

I’ve creating a drag and drop card game in AS 2.0
and need to set the cards randomly in set positions every time the game is played. no two cards can be in the same space, so the taken position needs to be taken out of the array.
I am not concerned about the Y value just X .
I think this needs to be an array containing the positions. then using slice to remove the value from the array. I’m not sure how to assigned the array position to the movie clip.
Any help will be much appreciated