var prefix = "images/btnFramework/";
var images = new Array("btn_whatisdigsig.jpg", "btn_whatisdigsig_o.jpg","btn_howitworks.jpg","btn_howitworks_o.jpg","btn_mediatypes.jpg","btn_mediatypes_o.jpg","btn_whyonelan.jpg","btn_whyonelan_o.jpg","btn_productrange.jpg","btn_productrange_o.jpg","prod_ntb204060.jpg","prod_ntb204060_o.jpg","btn_faqs.jpg","btn_faqs_o.jpg","btn_cta.jpg","btn_cta_o.jpg","btn_handbook.jpg","btn_handbook_o.jpg","btn_update.jpg","btn_update_o.jpg","btn_oxfordaward.jpg","btn_oxfordaward_o.jpg"); 
var preload = new Array();
 
for (var i = 0; i < images.length; i++ ) 
{ 
    preload[i]= new Image(); 
    preload[i].src = prefix + images[i];
}

function swap(i,s) 
{
    document.getElementById(i).src = prefix + s;
}