Probability question for all you math guys....

[Wayfare]

You and your friend are playing a game. You take a standard 52-card deck and pull a card. If it is black, your friend pays you a dollar. If it is red, you pay him a dollar. You do not shuffle the deck after picking each card. You have the power to continue playing until the deck is used up, or to stop at any time.

At what point should you stop the game? What is the average EV for you playing this game?