Bigbruin.com has published a review on Amazon Prime Instant Video for Windows Media Center

I am a big fan of Windows Media Center, and presently use it to manage the entertainment duties on my family's primary televisions and all computers. It is used to handle Blu-ray/DVD playback, networked stored movie playback, Netflix, local and Internet based streaming music, as well as live TV thanks to a pool of 6 tuners shared over the network. One thing I have been very disappointed in is the lack of an add-in to allow me to take advantage of all the "free" movies and TV shows available to me as an Amazon.com Prime member. So many devices support Prime videos that it seemed ridiculous to me that something wasn't available for Media Center users.

  Amazon Prime Instant Video for Windows Media Center