VS 2008, ASP.NET Development Server, .xslt vs .xsl filename extension

MS VS 2008, .xslt vs .xsl filename extension

Add New Item "Wizard" generates by default .xslt extension. The file is then served by magic cassini (ASP.NET Development Server) when testing locally.

All works fine until you try to load xslt file with XMLHttpRequest.
Cassini sends incorrect Content-Type:

HTTP/1.1 200 OK
Server: ASP.NET Development Server/9.0.0.0
Date: Tue, 07 Sep 2010 13:02:40 GMT
X-AspNet-Version: 2.0.50727
Cache-Control: private
Content-Type: application/octet-stream
Content-Length: 347
Connection: Close

and of course XHR (correctly) fails to provide xhr.responseXml property.

Questions:
How can you configure ASP.NET Development Server or .NET web application to serve "correct Content-Type"?
What is the "correct Content-Type" anyway ?
Will be XHR capable to read this "correct Content-Type" (XB of course)?

Thanx for one nice default
inconsistent with another one.

Because of using
twisted version of XHR and MSIE 7.0 it was hard to spot.

Solution ?

Use .xsl instead of .xslt.
ASP.NET Development Server servres them with text/xml Content-Type which seems to work ;-)