function onCoverLoad()
{   


    var imgCoverPage = document.getElementById("imgCoverPage");
    if (!imgCoverPage)
        return;

    // 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/Introduction1280x1024.gif";
            break;
            
        case "1024x768":
            imgCoverPage.src = "styles/images/Introduction1024x768.gif";
            break;	
            
         default: 
            imgCoverPage.src = "styles/images/Introduction1280x1024.gif";
            break;                   	    
	}  
}