I use this for my mouse overs with 2 images
<head>
<script language="JavaScript1.1">
<!--
var darkened_pics = new Array();
var lighted_pics = new Array();
var clicked_pics = new Array();
function preloadButtonSet(num,dark,light,clicked) {
darkened_pics[num] = new Image();
darkened_pics[num].src = dark;
lighted_pics[num] = new Image();
lighted_pics[num].src = light;
clicked_pics[num] = new Image();
clicked_pics[num].src = clicked;
}
// define the image swapping in the following format:
// preloadButtonSet(button_num,dark_button_src,light_button_src,clicked_button_src)
// -->
</script>
<script language="JavaScript">
<!--
function lighten(num) {
if (document.images){
eval("document.button"+num+".src = lighted_pics["+num+"].src;");
return true;
} else return false;
}
function darken(num) {
if (document.images) {
eval("document.button"+num+".src = darkened_pics["+num+"].src;");
return true;
} else return false;
}
function clicked(num) {
if (document.images) {
eval("document.button"+num+".src = clicked_pics["+num+"].src;");
setTimeout("document.button"+num+".src = darkened_pics["+num+"].src;",350);
return true;
} else return false;
}
// -->
</script>
</head>
<body>
<script language="JavaScript1.2">preloadButtonSet(1,"button_1_about_me.gif","button_2_about_me.gif","button_1_about_me.gif");</script><a href="about.html" target="main_frame" onMouseOver="self.status='Here you can find almost everything about me ---->>>>'; return lighten(1);" onMouseOut="self.status=''; return darken(1);" onClick="return clicked(1);"><img src="button_1_about_me.gif" name="button1" border="0" ALT="Here you can find almost everything about me ---->>>>"></a><br>
<script language="JavaScript1.2">preloadButtonSet(2,"button_1_pictures.gif","button_2_pictures.gif","button_1_pictures.gif");</script><a href="pictures.html" target="main_frame" onMouseOver="self.status='Here some pictures plus funny pictures of me!'; return lighten(2);" onMouseOut="self.status=''; return darken(2);" onClick="return clicked(2);"><img src="button_1_pictures.gif" name="button2" border="0" ALT="Here some pictures plus funny pictures of me!"></a><br>
<script language="JavaScript1.2">preloadButtonSet(3,"button_1_mail_me.gif","button_2_mail_me.gif","button_1_mail_me.gif");</script><a href="mail_me.html" target="main_frame" onMouseOver="self.status='Mailto:thunderthebest@hotmail.com'; return lighten(3);" onMouseOut="self.status=''; return darken(3);" onClick="return clicked(3);"><img src="button_1_mail_me.gif" name="button3" border="0" ALT="Mail me at .....@hotmail.com."></a><br>
Hope u can use it :D