Microsoft has now officially announced it will stop selling any Games for Windows Live titles through xbox.com and the Games for Windows Live software client. Existing games will be supported by the service, so long as you can find a copy in the wild and the game's publisher decides to support any online component or DLC through in-game purchases.
You have until August 22nd to purchase any content through xbox.com and the Games for Windows Live software client. After that, none of the digital titles will be available anywhere. Does this impact you? Let me know in the comments below!