Since Microsoft has already just recently added the digital distribution of Xbox 360 games via the Xbox Live service to the classic Xbox titles that they were already offering for digital sale, it comes as very little surprise that Microsoft will throw its hat into the ring of the PC digital distribution market space by selling titles via its Games for Windows Live market place.

The move by Microsoft will put the company in direct competition with Steam from Valve, which is the dominant digital distribution platform for the PC at the moment. According to our sources, Microsoft is hopeful that the unique look and feel (when combined with the Games for Windows Live experience) will work in the company's favor and have customers choosing their service when purchasing PC game downloads.

Some fear that Microsoft's move into this arena will spell the end of free add-on content for the PC versions of popular titles. Some think that Microsoft will start pushing developers toward a micro-transaction model for add-ons and additional content, as the company does with their Xbox Live Marketplace content. It is likely that Microsoft will at least test the concept of offering additional download content for sale once the initial rollout of the Game for Windows Live market place is completed.

Our sources whisper that Microsoft will be offering Resident Evil 5, Red Faction: Guerrilla and Battlestations: Pacific as some of the high profile titles that will be available for digital download when the service will go live on December 15th. In addition, Microsoft has been working with developers to offer some unique Live-enabled versions of downloadable older titles, such as World of Goo and Osmos.

The move by the company into the PC gaming digital distribution space should prove interesting. While the company has been working hard on their Games for Windows roadmap, the results so far have been mixed. Microsoft in many ways moved developers away from developing PC titles to developing for the original Xbox platform, only to have many developers abandon PC gaming development altogether; but lately, Microsoft has realized that gaming drove a lot of innovation on the PC platform and they need gaming development back for Windows. We are sure that many of the hardware manufacturers would love to see a resurgence of PC gaming, as it led to lots of sales of higher profit margin PC-related products.