I was looking for a way to print an RTF document to the browser however when I used this header:
.. IE just prompet me to download.
So after hunting around a bit I found the answer to the problem.. IE won't display the output in the browser unless you have a .rtf extension. So that means in Apache you must put something like this:
AddType application/x-httpd-php .php4 .php .php3 .phtml .rtf
NB: Don't forget to use the header still.