function centerPopNav(url,name,size_w,size_h) {
	var win_w=size_w;
	var win_h=size_h;
	
	if (win_w>=screen.width) win_w=parseInt((screen.width-size_w)/2);
	if (win_h>=screen.height) win_h=parseInt((screen.height-size_h)/2);
	
	var features='scrollbars=yes,resizable=yes,width='+win_w+',height='+win_h
	+',left='+((screen.width/2)-(win_w/2))+',top='+((screen.height/2)-(win_h/2));
	popNav(url,name,features);
}

function popNav(url,name,features) {
	//Browser Detection
	var oldPopStyle = false;
	if (navigator.appName == "Microsoft Internet Explorer" && parseInt(navigator.appVersion) < 4)
		oldPopStyle=true;
	window.name='mainWin';
	if (oldPopStyle)
		popBox = window.open(url,name,features); 
	else {
		popBox = window.open(url,name,features);
		popBox.focus();
	}
}

function liveHelpStart() {
	centerPopNav('http://viztek.qwsi.com/isaacstore/livehelp.asp','sitechat',600,400);
}