I was somewhat disappointed to discover that a windows media center background addin cannot receive PlayState or PlayRate events from the host process. This makes sense at one level in that the AddIn is hosted out-of-process from the host media center application (at least starting in Windows XP MC Edition Update Rollup 2). I guess it would have been nice though if Microsoft had thought to supply a mechanism within the Media Center SDK that would enable compensate for this. So for now, I'm forced to poll the properties at regular intervals and write my own little routine to raise events internal to my application. Maybe Windows 7 Media Center will have some improvements here... I'll be watching :)