If you plan to use Silverlight for Windows Embedded on an i.MX53 from Freescale, give a look at:
http://www.adeneo-embedded.com/en/About-Us/News/Silverlight-OpenGL-Rendering-Plug-in-iMX53-QSb
Adeneo Embedded developed an OpenGL rendering plugin that will offload most of the rendering to the dedicate hardware and will provide a more responsive UI leaving plenty of CPU cycles for your own code.
This will lead to a better user experience for the end-users of your devices.