if (document.images) {
	logoon = new Image(); logoon.src = "graphics/ad_logo_over.jpg";
	homeon = new Image(); homeon.src = "graphics/buttons/ad_over_home.jpg";
	contacton = new Image(); contacton.src = "graphics/buttons/ad_over_contact.jpg";
	abouton = new Image(); abouton.src = "graphics/buttons/ad_over_about.jpg";
	institutionalon = new Image(); institutionalon.src = "graphics/buttons/ad_over_institutional.jpg";
	individualon = new Image(); individualon.src = "graphics/buttons/ad_over_individual.jpg";
	
	logooff = new Image(); logooff.src = "graphics/ad_logo.jpg";
	homeoff = new Image(); homeoff.src = "graphics/buttons/ad_off_home.jpg";
	contactoff = new Image(); contactoff.src = "graphics/buttons/ad_off_contact.jpg";
	aboutoff = new Image(); aboutoff.src = "graphics/buttons/ad_off_about.jpg";
	institutionaloff = new Image(); institutionaloff.src = "graphics/buttons/ad_off_institutional.jpg";
	individualoff = new Image(); individualoff.src = "graphics/buttons/ad_off_individual.jpg";
}

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

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