Eric, thanks for that. I read the thread and then tried my self. I set up a link to images/test.pdf using protocol 'other'.
I then went to the images icon and under Image Properties/Image Info (NOT the upload tab) browsed for my pdf and uploaded it. If I used the upload tab it said "Invalid File type'.
After uploading OK I tested the page and hey presto the pdf displayed. This works with Word files too!
Am I doing it right or have I found a work around others havent? Please see the test site at www.oxeyes.org!