Upon further investigation I found the problem was related to an absolute path for the image. I am currently using JoomlaFCK Editor and found that there is a know bug at that the time of this post (
http://joomlacode.org/gf/project/joomlafck/)
The editor puts in an absolute path. If you were to View Source and change the path manually to a relative path (i.e. /images/stories/myimage.jpg) then McAfee does not treat it as being served dynamically - triggering the security suite to block the image.
On to looking for a different editor...