How do I buy Grand Theft Auto IV: The Lost and Damned?
Starting February 17th, 2009 worldwide at 3:00 AM Eastern Standard Time, simply go to Xbox LIVE Marketplace with your connected Xbox 360 console and purchase the Grand Theft Auto IV: The Lost and Damned download for 1600 Microsoft Points ($19.99).
A disc-less retail version is also available which will contain a unique code to purchase and download The Lost and Damned through the Xbox LIVE Marketplace.
Grand Theft Auto IV: The Lost and Damned requires a copy of the original GTA IV release for Xbox 360 - but you can play it even if you haven't finished Niko's story.
If you haven't registered an Xbox LIVE account, you can do so online by clicking http://www.xbox.com/en-US/live/joinlive.