Doing this in a non-hosted mode would be a piece of cake. However, throwing hosting into the mix might be a bit tricky.
Just to see if I can give you or someone else an idea on how to fix your issue, I will describe how to do it normally.
-Use https:// only with SharePoint (meaning, have no AAM that uses the http version of your namespace)
-Create a new IIS virtual server with the host header of your site, listening on port 80
-Make the new virtual server redirect to https
-Use anonymous on the new IIS virtual server
Using these steps, you wouldn't get two prompts....but like I said, having hosting makes it a bit complicated.
Sorry I can't be of more help right now....
-dggcoop, MCTS
Cick here for my blogPlease do not email me your SharePoint questions! If you need SharePoint help, please post your question in the appropriate SharePointU.com forum.
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