If you like to work in Flash only, I would recommend:
http://www.entheosweb.com/Flash/load...nal_images.asp
So you can minimize load time. As it is, most map users would likely not view all available maps in one sitting, so if you can break it down to loading just the main map at run time and calling individual images (maps) in response to the onclick events I think it would be much quicker.
By the way, I think I was a bit brief in my first post, but nice job! Looks very well polished.