I just added a new blog post on my team blog about how to convert numbers from Arabic to Indic. The nice thing is this post works for any platform not only Silverlight. It also include the complete Silverlight code sample to demo this conversion. So read the full details at our team blog http://blogs.msdn.com/b/global_developer/archive/2011/02/24/display-arabic-digits-in-silverlight.aspx