DirectX 10.1 will help Windows 7 to scale better from low end to high-end hardware and put it in good use especially when it comes to user interface. Shaders will be used for the Glass and Windows 7 memory consumption is cut by 50 percent per window, something that memory manufacturers and GPU guys might not really appreciate.
Windows 7 will also have richer thumbnail animations and at the same time it comes with Media Center user interface, Video playback and Desktop Window Manager (DWM), all borrowed from Vista. We are not aware of any improvements in these area compared to Vista.
We are sure that these features will also work on DirectX 10.0 hardware but Microsoft has decided to promote DirectX 10.1 support this time.