New features 

• Include Hardware Decode of H.264 media, which provides a significant performance improvement with decoding of unprotected content using the GPU
• Postscript Vector Printing to improve output quality and file size
• Improved graphics stack with 3D support that uses the XNA API on the Windows platform to gain low-level access to the GPU for drawing vertex shaders and low-level 3D primitives.

• In addition, extends the ‘Trusted Application’ model to the browser for the first time. These features, when enabled via a group policy registry key and an application certificate, mean users won’t need to leave the browser to perform complex tasks such as multiple window support, full trust support in browser including COM and file system access, in browser HTML hosting within Silverlight, and P/Invoke support for existing native code to be run directly from Silverlight.