function changeImage(imageId, imageOut, imageOver) {
	var image = document.getElementById(imageId);
	if (!image.src.match(imageOver)) {
		image.onmouseout = function() {
			image.src = imageOut;
		}
		image.onmouseover = function() {
			image.src = imageOver;
		}
	}
}

function changeImages() {
	changeImage("but-particulier", "images/but_particulier.jpg", "images/but_particulier_over.jpg");
	changeImage("but-ondernemers", "images/but_ondernemers.jpg", "images/but_ondernemers_over.jpg");
	changeImage("search", "images/search.gif", "images/search_over.gif");
}

function addEvent(target, type, listener, useCapture) {
	if (target.addEventListener) {
		target.addEventListener(type, listener, useCapture);
	} else if (target.attachEvent) {
		target.attachEvent("on" + type, listener);
	}
}

addEvent(window, "load", changeImages, false);