Not PHP specific, but need help anyways

Howdy-- I have a PHP script that creates links to external files that I want the user to save to disk. Specifically these are Postscript Printer Definition files (PPDs) which will be saved on a Mac or a PC. As it is, I use the following link: <a href="http://www.mypage.edu/printer.ppd"> etc... This browses to the file and shows up in the browser. What I want is when the user chooses the link, it brings up the "Save To Disk" dialog (for both Mac and PC). Should I use the <a href="ftp:// etc.."> tag? I was under the impression you needed an FTP server for that to work right. Any hints, or a shove in the right direction please. Thanks RDB