function toggle() {
	source = this.getAttributeNode("src").nodeValue;
	var newSource = document.createAttribute("src");
	newSource.nodeValue = "http://www.speedheads.de/";
	if (source.substr(source.length-7) == "_on.gif") {
		newSource.nodeValue = source.substr(0, source.length-7);
	} else {
		newSource.nodeValue = source.substr(0, source.length-4)+"_on";
	}
	newSource.nodeValue += ".gif";
	this.setAttributeNode(newSource);
}

function colorize() {
	partners = document.getElementById("partnerlist").getElementsByTagName("img");
	for (i=0; i<partners.length; i++) {
		partners[i].onmouseover = toggle;
		partners[i].onmouseout = toggle;
	}
}

window.onload = function() {
	colorize();
}