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There are already games in development that will use DX10, and are using DX10 now. This article, posted yesterday, discusses how Crysis is getting DX10 code builds on an almost daily basis, and is working with prototype DX10 hardware
. Apparently there is also footage of actual DX10 code on DX10 hardware in action. (Probably due to the early nature of both they have not released this mainstream for comparison to DX9.) So no, games will
be out when Vista and DX10 GPUs hit the shelves that do take advantage of the hardware. How many besides Crysis? Well, I can't really say. The only ones I know for sure, due to the press surrounding them, are Crysis and the enhanced Halo 2.
Many of the changes we won't even see. It is very possible that a game uses the DX10 code but doesn't use any new features that DX9 can't run. However, by doing that the coding work is a lot easier on the developer and the game will run faster and smoother due to the way DX10 communicates with the OS.
Some of my memory is getting rusty on this, but it's all right there in my DX10 thread.
Also, I’m sure more and more news will start to surface very quickly as the nVidia DX10 GPUs are rumored to be set for a September launch.