var img_dir = 'images';
if(document.images) {
	var aboutRoll = new Image();
	var serviceRoll = new Image();
	var clienteleRoll = new Image();
	var supportRoll  = new Image();
	aboutRoll.src = img_dir + '/about.gif';
	serviceRoll.src = img_dir + '/service.gif';
	clienteleRoll.src = img_dir + '/clientele.gif';
	supportRoll.src = img_dir + '/support.gif';
}
function roll(imgName) {
	document.images[imgName].src = img_dir + '/' + imgName + '_over.gif';
}
function rollOut(imgName) {
	document.images[imgName].src = img_dir + '/' + imgName + '.gif';
}