A big thanks to you and the others that helped me.
I'm now setting the media-type in the ASP page as it fits me. :)

Isn't it weird that the transformation gives me HTML (for
instance the meta
tag is not closed, neither is link tag), but STILL the
media-type is xml?

No, the http server decides the media-type in a number of ways, depending on
various configuration files; but unless there's some close integration
between the http server and the XSLT engine, it's not going to take account
of either the contents of the file or the attributes set in xsl:output.

Michael Kay
http://www.saxonica.com/