Multipurpose Internet Mail Extensions (MIME) is a wonderful thing,
allowing your Web browser to automatically display content of many
different formats natively within the browser window. However,
sometimes, you may want users to download this content to their
client computer rather than simply viewing it in the browser. But
how do you override the browser's determination to render known
MIME types itself? The answer is to use a content disposition
header in your Web page.
Suppose you've written an ASP page that contains a link to a known
MIME type, but you want the user to download the file instead of
viewing it. Add the following to your script:
response.addHeader "content-disposition", "attachment;
filename=filename.ext"
Then substitute the actual filename and extension, and it's as good
as done. When your users click on the link, they'll immediately see
the download dialog box instead of the file's contents.