var isIE4; 
var isNav4;
var isNav6; 

function detectBrowser()
{ 
	if (navigator.appVersion.charAt(0) == "4") {
		if (navigator.appName.indexOf("Explorer") >= 0) {
			isIE4 = true;
		}
		else {
			isNav4 = true;
		}
	}
	else if (navigator.appVersion.charAt(0) > "4") {
		isNav6 = true;
	}
}

detectBrowser();