Forcing download instead of browsing from an FTP site

If you have certain files for download from an FTP site...
Images, Word documents, PDF files, etc., etc. if you setup an FTP link on a web page, i.e.

<A HREF="ftp://locahost/downloads/verybigimage.gif">Click HERE</A>

the image, etc. will actually appear in the browser. So the client then has to save the particular file from the browser. What I want is to force is downloading of the file, i.e.

So the FILE DOWNLOAD dialog box appears allowing you to either OPEN or SAVE the file.

(Just like what happens if you link to an EXE or ZIP file)

Is this possible?

Otherwise I'll just have to make sure all files are ZIPped on the FTP site.