In some cases, the device or program might not work or may require an update, or you might need to uninstall some programs, and then reinstall them after installing Windows 8.1 Preview.
With every new release, Microsoft strives to offer a high degree of compatibility with all apps and devices. Microsoft regularly tests thousands of apps and devices and gathers customer feedback in order to help identify and fix compatibility issues. However, there are a few classes of products, like security and system utilities, that typically aren't compatible across Windows versions because they depend on internal parts of Windows.