Source: Beyond3d
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Since the first Direct3D 10 beta was published more than a year ago, the new API has only worked on Microsoft's Vista operating system. Most people believe that this limitation was only introduced to improve sales of Microsoft’s newest version of Windows. One of the theories put forth is that even though Microsoft has limited the installation of some products to specific versions of Windows in the past, some talented hackers have been able to remove these limitations. It has been claimed that there are even examples of this phenomenon in the world of DirectX. Long time observers will recall that Microsoft did not allow the installation of DirectX 5 on Windows NT 4.0, but some enthusiasts made claims that they had it working. However, this is not the full truth. These people were able to get the runtime and the software devices working, but no one was able to get full hardware accelerated Direct3D on Windows NT 4.0. The reason for this is simple. The driver model used by Windows NT 4.0 doesn’t support 3D at all.