I get this question a LOT: "Why hasn't Intel released WDDM drivers for the 915 integrated graphics chipset? I can't run the fancy visual effects in Windows Vista, like Aero Glass, without one!"
People hardest hit by this issue include virtually all Tablet PC and UMPC users, along with lots and lots of people using laptops with that particular Intel integrated graphics chipset. I personally have two systems, a Lenovo X41 Tablet PC and an Asus R2H UMPC, that are affected. The Intel Software Network forum is full of complaints, rants, and even veiled threats on the topic - implying that we, Intel, are sitting on the driver, or not releasing it for some unknown reason (most speculate that it's because we want to force people to upgrade to a newer, more powerful graphics solution).
In this video, I sat down with Intel's Chuck DeSylva, right after he gave a presentation at GDC 2007 on the topic of optimizing your games to take advantage of the Intel G965 graphics chip. I asked him the million dollar question: Why are there no WDDM drivers for Intel 915 graphics?
Watch the video for the answer. It's about 3.5 minutes long, and weighs in at 22MB if you want to download it directly.
The short version (if you're impatient): The WDDM Vista driver spec came out long after the 915 design was complete and in production, and even though it has advanced features like Pixel Shader 2.0, there is a missing hardware feature, called the Hardware Scheduler, that 915 lacks, and without that, it doesn't meet the WDDM spec from Microsoft, and we (Intel) can't release a WDDM driver for it.
There. It's done. I hope that answers your questions. Please link your friends and associates to this video/post for the "definitive" answer.
As always, we're open to your feedback, so please feel free to post a comment, respond in the ISN forums, or contact me directly if you have any more questions or issues.