if (document.images) {

	nav_about_off = new Image();
	nav_about_off.src = "images/nav_about_off.gif";
	nav_about_on = new Image();
	nav_about_on.src = "images/nav_about_on.gif";  
   
	nav_after_off = new Image();
	nav_after_off.src = "images/nav_after_off.gif";
	nav_after_on = new Image();
	nav_after_on.src = "images/nav_after_on.gif";

	nav_calendar_off = new Image();
	nav_calendar_off.src = "images/nav_calendar_off.gif";
	nav_calendar_on = new Image();
	nav_calendar_on.src = "images/nav_calendar_on.gif";
   
	nav_contact_off = new Image();
	nav_contact_off.src = "images/nav_contact_off.gif";
	nav_contact_on = new Image();
	nav_contact_on.src = "images/nav_contact_on.gif";

	nav_curriculum_off = new Image();
	nav_curriculum_off.src = "images/nav_curriculum_off.gif";
	nav_curriculum_on = new Image();
	nav_curriculum_on.src = "images/nav_curriculum_on.gif";

	nav_homework_off = new Image();
	nav_homework_off.src = "images/nav_homework_off.gif";
	nav_homework_on = new Image();
	nav_homework_on.src = "images/nav_homework_on.gif"; 
   
	nav_life_off = new Image();
	nav_life_off.src = "images/nav_life_off.gif";
	nav_life_on = new Image();
	nav_life_on.src = "images/nav_life_on.gif";   

	nav_login_off = new Image();
	nav_login_off.src = "images/nav_login_off.gif";
	nav_login_on = new Image();
	nav_login_on.src = "images/nav_login_on.gif";    

	nav_parents_off = new Image();
	nav_parents_off.src = "images/nav_parents_off.gif";
	nav_parents_on = new Image();
	nav_parents_on.src = "images/nav_parents_on.gif";    
   
	nav_principal_off = new Image();
	nav_principal_off.src = "images/nav_principal_off.gif";
	nav_principal_on = new Image();
	nav_principal_on.src = "images/nav_principal_on.gif";
   
	nav_resources_off = new Image();
	nav_resources_off.src = "images/nav_resources_off.gif";
	nav_resources_on = new Image();
	nav_resources_on.src = "images/nav_resources_on.gif";   

	nav_teachers_off = new Image();
	nav_teachers_off.src = "images/nav_teachers_off.gif";
	nav_teachers_on = new Image();
	nav_teachers_on.src = "images/nav_teachers_on.gif";   

	nav_webmail_off = new Image();
	nav_webmail_off.src = "images/nav_webmail_off.gif";
	nav_webmail_on = new Image();
	nav_webmail_on.src = "images/nav_webmail_on.gif";  

	nav_home_off = new Image();
	nav_home_off.src = "images/nav_home_off.gif";
	nav_home_on = new Image();
	nav_home_on.src = "images/nav_home_on.gif";
      
	nav_guidance_off = new Image();
	nav_guidance_off.src = "images/nav_guidance_off.gif";
	nav_guidance_on = new Image();
	nav_guidance_on.src = "images/nav_guidance_on.gif";      
      
      
}

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

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