Windows Vista came with a lot of hype and hoopla but it fell short in many ways. The primary changes were emphasized more on driver models and the interface of the OS while the interface improvements were comparatively ignored, hence the OS became cumbersome and the performances were often hampered. Problems with the drivers resulted in a decline in the performance for the period of more than a year. It was a frustrating period for users stuck with Vista.
The OS went through several modifications and improvements and whatever creases were there has been ironed out hence the present Vista has become more reliable in performance. But the reputation has already been inked and Vista is referred to as a cumbersome system that keeps on crashing in a jiffy. In fact the situation came to that that a lot of users preferred XP to Windows Vista.
The 3D graphics suffered most from the drawbacks of Vista, the newly developed WDDM 1.0 driver model was quite a new road from the stuff that was used in XP, and while it was projected to improve performance it resulted otherwise. Graphics drivers mostly from Nvidia resulted in frequent OS crashes in the initial period of Vistas release. The Gamers were not satisfied as they refused to let go off 10% of their graphics performance. And why should they after all the money they are shelling out for gaming experience.
windows 7 is working like anti Vista. There are a lot of clandestine changes but no new and different driver models are introduced. WDDM 1.1 is a slight variation to the display driver model and ATI and Nvidia should have an easy go with their performance with stability and speed as much as Vista.
ATI has already announced they will add Windows 7 Drivers in their monthly drivers updates much before the Win 7 release. Nvidia has also done likewise with their new Win 7 drivers with more updates to arrive. All we have to look forward is to the gamers who will make the final verdict on which OS will give them better performance Windows 7 or Vista?