function newImage( imgSrc ){

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

 return imgName;

}

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

if (document.images)
 {

 company_over = newImage("images/companyon.jpg");
 strategy_over = newImage("images/strategyon.jpg");
 properties_over = newImage("images/propertieson.jpg");
 casestudies_over = newImage("images/casestudieson.jpg");
 contact_over = newImage("images/contacton.jpg");
 }