var UserCheck = new UpUserCheck();
if(!UserCheck.Browser.compatible)
	alert('incompatible browser version');
function UpUserCheck()
{
	this.Browser = new BrowserCheck();
}
function BrowserCheck()
{
	var Browser = new BrowserVersion();
	if(Browser.mz5up||Browser.ns6up||Browser.ie4up)
	{
		this.compatible = true;
	}
	else
	{
		this.compatible = false;
	}
}
function BrowserVersion()
{
	var agent  = navigator.userAgent.toLowerCase();
	var appVer = navigator.appVersion.toLowerCase();
	var ns6Pos = agent.indexOf('netscape6');
	var iePos  = appVer.toLowerCase().indexOf('msie');
	if (ns6Pos !=-1)
	{
		this.minor = parseFloat(agent.substring(ns6Pos+10))
		this.major = parseInt(this.minor)
	}
	else if (iePos !=-1)
	{
		this.minor = parseFloat(appVer.substring(iePos+5,appVer.indexOf(';',iePos)))
		this.major = parseInt(this.minor);
	}
	else
	{
		this.major = parseInt(navigator.appVersion);
		this.minor = parseFloat(navigator.appVersion);
	}
	this.opera = ((agent.indexOf("opera")!=-1));
	this.ns    = ((agent.indexOf('mozilla')!= -1) &&
				((agent.indexOf('spoofer')== -1) &&
				(agent.indexOf('opera')==-1) &&
				(agent.indexOf('compatible')== -1)));
	this.mz5up = ((agent.indexOf('mozilla')!=-1)&&(this.major>=5))
	this.ns6up = (this.ns && (this.major >= 6));
	this.ie    = (agent.indexOf("msie")!= -1 && !this.opera);
	this.ie4up = (this.ie && (this.major >= 4));
}