What should I consider before creating a Silverlight website?

Question

I have opted to use silverlight for a website. This runs in all major browsers. The application could be highly graphically intensive. What have I missed?

Edit:

It runs on Android and other mobile platforms?

I have since written about this here: http://carnotaurus.tumblr.com/post/4921541502/old-school-game-to-be-written-in-silverlight