var rolling = false;
var imgs = new Array();
function preload() {
	if (document.images) {
		var dir = arguments['0'];
		for (var i=1; i<arguments.length; i++) {
			imgs[arguments[i]+'_on'] = new Image();
			imgs[arguments[i]+'_on'].src = dir +arguments[i]+'_on.gif';
			imgs[arguments[i]] = new Image();
			imgs[arguments[i]].src = dir+ arguments[i]+'.gif';
		}
	}
	rolling = true;
}
function rollIn(imgName)
	{
		if (document.images && rolling)
		{
			document.images[imgName].src=imgs[imgName+'_on'].src
		}
	}

function rollOut(imgName)
	{
		if (document.images && rolling)
		{
			document.images[imgName].src=imgs[imgName].src
		}
	}