var imgLoaded = false;

	var nav1_on, nav1_off, nav2_on, nav2_off, nav3_on, nav3_off, nav4_on, nav4_off
	var nav5_on, nav5_off, nav6_on, nav6_off, nav7_on, nav7_off, nav8_on, nav8_off

	function initNavigation() {
		if (document.images) {

			// Home
			nav1_on = new Image();
			nav1_off = new Image();
			nav1_on.src = "/nl/images/nav_home_onmouse.gif";
			nav1_off.src = "/nl/images/nav_home.gif";

			// Mission
			nav2_on = new Image();
			nav2_off = new Image();
			nav2_on.src = "/nl/images/nav_mission_onmouse.gif";
			nav2_off.src = "/nl/images/nav_mission.gif";

			// What
			nav3_on = new Image();
			nav3_off = new Image();
			nav3_on.src = "/nl/images/nav_what_onmouse.gif";
			nav3_off.src = "/nl/images/nav_what.gif";

			// How
			nav4_on = new Image();
			nav4_off = new Image();
			nav4_on.src = "/nl/images/nav_how_onmouse.gif";
			nav4_off.src = "/nl/images/nav_how.gif";

			// Results
			nav5_on = new Image();
			nav5_off = new Image();
			nav5_on.src = "/nl/images/nav_results_onmouse.gif";
			nav5_off.src = "/nl/images/nav_results.gif";

			// Bio
			nav6_on = new Image();
			nav6_off = new Image();
			nav6_on.src = "/nl/images/nav_bio_onmouse.gif";
			nav6_off.src = "/nl/images/nav_bio.gif";

			// Contact
			nav8_on = new Image();
			nav8_off = new Image();
			nav8_on.src = "/nl/images/nav_contact_onmouse.gif";
			nav8_off.src = "/nl/images/nav_contact.gif";

			imgLoaded = true;
		}
	}

	function onNavigationOn(buttonNr) {
  		if (imgLoaded)
			if (isIE)
				document.images['nav'+buttonNr].src = eval('nav'+buttonNr+'_on.src')
			else
				document.layers['content'].document.images['nav'+buttonNr].src = eval('nav'+buttonNr+'_on.src')
	}

	function onNavigationOff(buttonNr) {
  		if (imgLoaded)
			if (isIE)
				document.images['nav'+buttonNr].src = eval('nav'+buttonNr+'_off.src')
			else
				document.layers['content'].document.images['nav'+buttonNr].src = eval('nav'+buttonNr+'_off.src')
	}