// create an array of the URLs of all images that are to 
// appear in the rollovers

var pics = new Array("images/nav_home_up.jpg","images/nav_gallery_up.jpg","images/nav_proofs_up.jpg");

// create a new empty array

var preload = new Array();

// insert a new Image object into each empty element
// then assign each image URL to the Image objects  

for(var i = 0; i < pics.length; i++ )
{
  preload[ i ] = new Image();
  preload[ i ].src = pics[i];
}