I believe when you use Fireworks to create hotspots in an image it creates a html file that has all map tag coordinates, these need to be used in conjunction with the image. When you hit the preview button I think it auto creates a temporary html file. One way to verify this is that you preview the image, then right click on the preview page and choose view source you might see something like:
<map name="planetmap">
<area shape="rect" coords="0,0,82,126" href="sun.htm" alt="Sun" />
<area shape="circle" coords="90,58,3" href="mercur.htm" alt="Mercury" />
<area shape="circle" coords="124,58,8" href="venus.htm" alt="Venus" />
</map>
OR Fireworks might be creating javascript which, I don't believe you can stick in a email anway.
As a work around (if you have just one link per image) you could just insert the image into your email and make it a link through normal outlook 2003 controls.
If you know someone with a little web programming skills, sending an html email isn't very hard to do.