According to the Microsoft e-mails, Nvidia's drivers alone caused 28.8% of the crashes seen in Vista during the report period. (The report says only that it covers 2007, but it likely does not cover the entire year.) Microsoft drivers come in second at 17.9%, ATI is third with 9.3%, and Intel takes fourth place with 8.8%. Webroot Software, makers of an anti-spyware application, was next with 2.9%. All the other drivers, from hundreds of companies listed on the report, plus "Unknown", make up the other 32.3% of the crashes.
Cumulatively, this data shows that the Nvidia-ATI-Intel "Axis of Driver Evil" caused almost half of the crashes in Vista! What could Microsoft have done to prevent this problem? A longer beta period probably would not have worked. Vendors weren't going to get serious about making their stuff work with Vista until they were sure that Microsoft was serious about shipping Vista. (If this sounds like a game of chicken to you, then you understand the situation perfectly.) Reports from Nvidia users seem to indicate that their drivers are much better now, but the damage already has been done to Vista's reputation.
Vista's challenge to developers was in the multitude of new security and interface changes that happened "under the hood." Display drivers in particular got a totally new software interface called Windows Display Driver Model, or WDDM. Given the data, it seems likely that a lot of crashes were in drivers that used the new WDDM model. That should not be a surprise to Microsoft; it was a new software technology and nobody had experience with it.
If Microsoft wanted to improve Vista's quality, the best thing they could possibly have done would be to provide more support for driver developers. In particular, they should have carpet-bombed the major display hardware makers with assistance, treated them to "driver ed" classes, and even paired Microsoft experts with the hardware developers to make sure the drivers would be excellent. Or, as Steve Ballmer would say: "Developers, developers, developers, developers."