From the article: "If the names Zoey, Francis, Bill, and Louis don't mean much to you, then you probably haven't played the exceptional shooter Left 4 Dead. But if they trigger memories of gunning down endless hordes of zombies and desperately fighting for your life while screaming at your buddies, then you're quite familiar with Valve's thrilling cooperative multiplayer shooter, which shipped late last year. Now Valve is prepping the first batch of downloadable content for the game, which it is going to give away for free to both Xbox 360 and PC players sometime in March or April. What's in it? Well, we went to Valve this week to find out."