DirectX 10.1 is an extension to DX 10.0 by Microsoft available in Windows Vista Service Pack 1 Build 6001.16659 and Windows Server 2008 codenamed Longhorn . As per Softpedia, the new features of DirectX 10.1 can be divided into three general categories: new shading and texturing capabilities, anti-aliasing improvements, and tighter specifications, the details of which can be found in AMD-ATI’s whitepaper for DX 10.1.

Advantages include global illumination delivering lighting and shadow quality in real-time that matches the ray tracing techniques used in CG films, improved anti-aliasing techniques to clean up distracting shimmering artifacts, and tighter specifications for improved compatibility.

Utilizing the new features of DirectX 10.1 will require you to have a new GPU hardware such as ATI Radeon HD 3800. But it is obviously backward compatible with any graphic card.

To download Direct X 10.1 for Windows Vista, you will need to install Service Pack 1 through Windows Update Services using a registry hack.

Instructions:

1) Save this text file as File.cmd
2) Then run the batch file with elevated administrator privileges.
3) Install and reboot the computer after installing each update: KB935509, KB937287 and KB93837.
4) After the final reboot, you will get the option to download Windows Vista SP1 in Windows Update.
5) Verify that you have DirectX 10.1 by running dxdiag from the command prompt.