CSV output displayed in Excel or similar.

I have a PHP script that outputs several lines of comma separated values.. I would like to display this output in Excel without having to write the output to a file with a .csv extension and redirecting. I have tried setting the content-type: application/vnd.ms-excel and Excel isn't happy.. it complains that it can't open the file and on the odd chance that I do get it working, it doesn't read the file as csv.. anyone know what's going wrong here?? Incidentally, if I do save the info down to a .csv and open it, it works just fine.. but then I have a temporary file issue :-( Regards, Matthew Clark.