function onCoverLoad()
{   
    var imgCoverPage = document.getElementById("imgCoverPage");
    if (!imgCoverPage)
        return;
        
    var sFFMacPrefix = "";
    var bIsMac = (navigator.appVersion.indexOf("Mac") != -1);
    var bIsMozilla = (typeof(window.sidebar) != "undefined");
    if (bIsMac && bIsMozilla)
    {
        sFFMacPrefix = "FFMac_";
    }

    // check user screen resolution
    var nWidth = window.top.screen.width;
    var nHeight = window.top.screen.height;
    // set cover page by screen resolution
    var userScreenResolution = nWidth + "x" + nHeight;
    
    switch ( userScreenResolution )
	{   
        case "1280x1024":
            imgCoverPage.src = "styles/images/" + sFFMacPrefix + "Introduction1280x1024.gif";
            break;
            
        case "1024x768":
            imgCoverPage.src = "styles/images/" + sFFMacPrefix + "Introduction1024x768.gif";
            break;	
            
         default: 
            imgCoverPage.src = "styles/images/" + sFFMacPrefix + "Introduction1280x1024.gif";
            break;                   	    
	}  
}