function openModalWindow(divName, bgDivName) {
	var div = $(divName);
	var bgDiv = $(bgDivName);
	
	var docDim = Element.getDimensions(document.body);

	//get the size of the window and calculate where the box should be placed
	var wDim = getBrowserWindowSize();
	var dDim = Element.getDimensions(div);
	
	div.style.top = ((wDim.height - dDim.height) / 2) + 'px';
	div.style.left = ((wDim.width - dDim.width) / 2) + 'px';

	if (docDim.height > wDim.height) {
		wDim.height = docDim.height;
	}

	bgDiv.style.width = wDim.width + 'px';
	bgDiv.style.height = wDim.height + 'px';

	Element.show(div);
	Element.show(bgDiv);
}

function closeModalWindow(divName, bgDivName) {
	Element.hide(divName);
	Element.hide(bgDivName);
}

function getBrowserWindowSize() {
	var winW = 1000, winH = 750;

	if (parseInt(navigator.appVersion)>3) {
		if (navigator.appName=="Netscape") {
			winW = window.innerWidth;
			winH = window.innerHeight;
		}
		if (navigator.appName.indexOf("Microsoft")!=-1) {
			winW = document.body.offsetWidth;
			winH = document.body.offsetHeight;
		}
	}
	
	var rval = {
		width: winW,
		height: winH
	};

	return rval;
}