function newImage( imgSrc ){

 var imgName = new Image();
 imgName.src = imgSrc;

 return imgName;

}

function swap( imgName, imgLocation )
{
 document[imgName].src = imgLocation ;
}

var preloadFlag = false;
function loadImages()
{
 if (document.images)
 {
  homeover = newImage("images/homeover.gif");
  contactover = newImage("images/contactover.gif");
  sitemapover = newImage("images/sitemapover.gif");
  homeover = newImage("images/home.gif");
  contactover = newImage("images/contact.gif");
  sitemapover = newImage("images/sitemap.gif");

 preloadFlag = true;
 }
}