You need to set it in the ASP script you are loading in.
http://coveryourasp.com/Snippet.asp?snip=35
You can find a overview of MIME types at : http://www.utoronto.ca/webdocs/HTMLd.../mimetype.html
also : http://ppewww.ph.gla.ac.uk/~flavell/...tent-type.html should give you a quick intor to the content-type.
Also: search for MIME types or content-type at http://www.google.com