Not what you expect to hear at the start of a new consoles lifespan, usually midway or at the end when PC graphics are performing a fair bit better with some stand out titles. Then again Microsoft have always struggled with PC gaming and pushing the limits of game developers in fear of cut out large chunks of their market who wouldn't be able to run the games at full spec (and thus feel disadvantaged).

Also they don't have any massive PC only games like others such as Blizzard, Value, etc 

http://www.neowin.net/news/microsoft-says-it-has-renewed-focus-on-pc-gaming-details-coming-this-summer

Games for Windows requirements.

If you ever wondered what the criteria was then click: here

Its an interesting read for any game developer. I seriously wish Microsoft would push this more while taking some of the pressure off the developers so they can still release on other platforms (Mac and Linux really arn't that major a competitor). A fantastic target would be someone like Activision Blizzard to really kick things off! Especially with Windows 8 and Xbox coming to PC. They have a good follower in Capcom but need a few more big names signed up.

If more PC only games had the integration of Live I think they would rally a much bigger market for their live platform and could potentially up-sell other services to PC users as well.

Although people complain about Live on the PC and the DRM used I've found that once your past it and into the game, the games have been of a much better quality than none GFWL PC games. Some good examples are BioShock 2, Red Faction: Guerrilla, and Batman: Arkham Asylum. The only exception was Fable 3 with had shocking frame rates.

For a list of current and upcoming titles see the Wikipedia article: here (The big ones being Street Fighter X Tekken & Resident Evil 6