I'm not sure if I'm happy or sad that Microsoft has neglected the PC as a gaming platform. On one hand, I'm very happy with my Xbox 360 and maybe Microsoft could have done an equally good job on the PC. On the other hand, Valve have stepped in to provide everything that Microsoft should have provided and they have done an amazing job.
Valve's Steam content delivery system blows Games for Windows out of the water. It's better implemented, better integrated and is better value for consumers.