function newImage( imgSrc ){

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

 return imgName;

}

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

var preloadFlag = false;
function loadImages()
{
 if (document.images)
 {

 portfolio_over = newImage("images/portfolioOn.jpg");
 available_over = newImage("images/availableOn.jpg");
 managed_over = newImage("images/managedOn.jpg");
 team_over = newImage("images/teamOn.jpg");

 preloadFlag = true;
 }
}