This is an old topic, but I just stumbled on it and realized I never answered. Sorry it took so long.
Here's how you do it. All the pieces of the same color should have the same value. With the exception of the "(document.images)", anything in parentheses should be replaced with the proper data, the parentheses should not remain.
<html>
<head>
<title>Your Image Map</title>
</head>
<body>
<img name="(Large Pic Name Here)" src="(Large Pic URL Here)" width="(Large Pic Width Here)" height="(Large Pic Height Here)" border="(0 = off, 1 = on)" usemap="#(Large Pic Name Here)" alt="" />
<map name="(Large Pic Name Here)">
<area shape="poly" coords="186,382,194,262" href="(Target URL Here)" target="_blank" alt="(Title Here)"
onMouseOver="if(document.images) document.(Large Pic Name Here).src='(PopUp Image URL Here)';"
onMouseOut="if(document.images) document.(Large Pic Name Here).src='(Large Pic URL Here)';" />
<area shape="rect" coords="286,382,286,402" href="(Target URL Here)" target="_self" alt="(Title Here)"
onMouseOver="if(document.images) document.(Large Pic Name Here).src='(PopUp Image URL Here)';"
onMouseOut="if(document.images) document.(Large Pic Name Here).src='(Large Pic URL Here)';" />
</map>
</body>
</html>
<html>
<head>
<title>Your Image Map</title>
</head>
<body>
<img name="large_pic" src="large_pic.png" width="800" height="600" border="0" usemap="#large_pic" alt="" />
<map name="large_pic">
<area shape="poly" coords="186,382,194,262" href="http://forum.snitz.com/forum/default.asp" target="_blank" alt="Snitz Forums 2000"
onMouseOver="if(document.images) document.large_pic.src='small_pic1.png';"
onMouseOut="if(document.images) document.large_pic.src='large_pic.png';" />
<area shape="rect" coords="286,382,286,402" href="http://cnn.com" target="_self" alt="CNN International News"
onMouseOver="if(document.images) document.large_pic.src='small_pic2.png';"
onMouseOut="if(document.images) document.large_pic.src='large_pic.png';" />
</map>
</body>
</html>