function isSilverlightInstalled()
{
    
    var isSilverlightInstalled = false;

    try
    {
        //check on IE
        try
        {
            var slControl = new ActiveXObject('AgControl.AgControl');
            isSilverlightInstalled = true;
        }

        catch (e) 
        {
            //either not installed or not IE. Check Firefox
            if (navigator.plugins["Silverlight Plug-In"])
            {
                isSilverlightInstalled = true;
            }
        }
    }

    catch (e)
    {
        //we don't want to leak exceptions. However, you may want
        //to add exception tracking code here.
    }

    return isSilverlightInstalled;

}