Yahoo News has an article on PC gaming. They talk about the improved graphics that DirectX 10 will offer to PC gaming:
As the demands from game makers (and players) have grown increasingly complex, so too have the capabilities of DirectX. The software lets programmers tell the 3-D computer chips in graphics cards whether to simulate a wisp of smoke or a mirror's reflection.
DX10 not only makes games look better, it also promises to improve performance by simplifying how the graphics cards process video information and display it on the screen.
"It means the realism will take a dramatic jump," says Roy Taylor, vice president of content for Nvidia Corp., which makes 3-D video chips for computers. "It's going to look dramatically more real."
Those effects have taken on a cinematic quality with DX10.
"We can create a world that looks and feels more real and is more responsive," Roper said. "We have volumetric fluid smoke that responds to objects that pass through it. We have soft shadows that get softer with distance from the caster."
Of the few DX10 games currently available, including Microsoft's own "Flight Simulator X," differences between DX10 and its predecessor, DX9, are dramatic, with water and atmospheric effects that look more like an actual video recording than a computer approximation of reality.