"Microsoft is currently working on a large update to the Direct3D API.
Originally called Windows Graphics Foundation, DirectX 10, and later DirectX
Next, but currently referred to as Direct3D 10, it will appear as part of
Windows Vista. Version 10 will represent a departure from the driver model of
DirectX Graphics 9.0, with the addition of a scheduler and memory
virtualization system. Direct3D 10 will forego the current DirectX practice
of using "capability bits" to indicate which features are active on the
current hardware. Instead, Direct3D 10 will define a minimum standard of
hardware capabilities which must be supported for a display system to be
"Direct3D 10 compatible". According to Microsoft, Direct3D 10 will be able to
display graphics up to 8 times faster than DirectX Graphics 9.0c. In
addition, Direct3D 10 will incorporate Microsoft Shader Model 4.0."
In short, DirectX 10 is not backwards compatible with DirectX 9, and thus,
it is up to the hardware/driver makers to get your games working.
