function BilderVorladen()
{
    document.Vorladen = new Array();
 
    if(document.images)
    {
        for(var i = 0; i < BilderVorladen.arguments.length; i++)
        {
            document.Vorladen[i] = new Image();
            document.Vorladen[i].src = BilderVorladen.arguments[i];
        }
    }
}

BilderVorladen("images/header_img_1.jpg","images/header_img_2.jpg","images/header_img_3.jpg","images/header_img_4.jpg","images/header_img_5.jpg","images/header_img_6.jpg","images/header_img_7.jpg","images/header_img_8.jpg","images/header_img_9.jpg","images/header_img_10.jpg","images/header_img_11.jpg");

function imageCOn(name) {
	document.fotos.src='images/header_img_'+name+'.jpg';	
}

function imageCOff(name) {
	document.fotos.src='images/header_img_'+name+'.jpg';
}