setContentType

Hi,

I have a servlet which generates a comma separated value(CSV) file and the
browser will prompt a dialog so the user can save the output file
to a preferred location. It works fine on Netscape Navigator but when I
use IE6 I got the following error

"Internet Explorer was not able to open this Internet site. The requested
site is either unavailable ro cannot  be found.
 Please try again later".

I use the following statement
setContentType( "text/comma-separated" )
and I can get around it with
setContentType("text/plain");

but the browser will just display the plain text instead of a dialog box.

What MIME type shall I use so a dialog will prompt in both IE and
Netscape.

Thanks,

-Alvin Chang