Hola unanime
Probá esto:
<img src=area1.jpg name=dibu width=100 height=100>
<a href="uno.html" onmouseover="dibu.src='area2.jpg'" onmouseout="dibu.src='area1.jpg'">uno</a>
<a href="dos.html" onmouseover="dibu.src='area3.jpg'" onmouseout="dibu.src='area1.jpg'">dos</a>
Suerte
