if (document.images) { 

     newson = new Image();      
     newson.src = "navigation/news_on.gif"; 
     abouton = new Image(); 
     abouton.src = "navigation/about_on.gif";  
     liston = new Image();
     liston.src = "navigation/list_on.gif";
     memberon = new Image();
     memberon.src = "navigation/member_on.gif";
     resourceson = new Image();
     resourceson.src = "navigation/resources_on.gif";
     contacton = new Image();
     contacton.src = "navigation/contact_on.gif";
     homeon = new Image();
     homeon.src = "navigation/home_on.gif";
         
     newsoff = new Image();      
     newsoff.src = "navigation/news_off.gif"; 
     aboutoff = new Image(); 
     aboutoff.src = "navigation/about_off.gif";  
     listoff = new Image();
     listoff.src = "navigation/list_off.gif";
     memberoff = new Image();
     memberoff.src = "navigation/member_off.gif";
     resourcesoff = new Image();
     resourcesoff.src = "navigation/resources_off.gif";
     contactoff = new Image();
     contactoff.src = "navigation/contact_off.gif";
     homeoff = new Image();
     homeoff.src = "navigation/home_off.gif";     
        }

function rollOn(imgName) {
        if (document.images) {
     document[imgName].src = eval(imgName + "on.src");
        }
}
         
function rollOff(imgName) {
        if (document.images) {
     document[imgName].src = eval(imgName + "off.src");
        }
}