To commemorate the merging
of the Games for Windows Marketplace
with Xbox.com, Microsoft has announced that they are giving away One Million Microsoft Points
from July 25th to August 1st, while supplies last. The promotion is for the US only I'm afraid.
This means that the first 2,500 qualifying online Games for Windows Marketplace purchases will be awarded with a free code for 400 MSP, which is sent to the e-mail tied to your GFWL account within 4-6 weeks, limit one per person. It isn't clear at this time if free content qualifies, as there are a few items that cost nothing at all. Otherwise there are many other games and add-ons to choose from in the Games for Windows Marketplace