if (document.images) {

            img1on = new Image();      		// Active Images
            img1on.src = "../../../images/nav_home_on.gif"; 
            img2on = new Image(); 
            img2on.src = "../../../images/nav_books_on.gif";  
            img3on = new Image();
            img3on.src = "../../../images/nav_faq_on.gif";
            img4on = new Image();
            img4on.src = "../../../images/nav_about_on.gif";                

            img1off = new Image();         	// Inactive Images
            img1off.src = "../../../images/nav_home_off.gif"; 
            img2off = new Image(); 
            img2off.src = "../../../images/nav_books_off.gif";  
            img3off = new Image();
            img3off.src = "../../../images/nav_faq_off.gif";
            img4off = new Image();
            img4off.src = "../../../images/nav_about_off.gif";                
	   }

// Function to 'activate' images.

function imgOn(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "on.src");
		
        }
}

// Function to 'deactivate' images.

function imgOff(imgName) {
        if (document.images) {
              document[imgName].src = eval(imgName + "off.src");
				
        }
}