function preLoadImgs()
{
	tab1_on 		= new Image();
	tab1_on.src 	= "images/nav/home_on.png";
	tab1_off 		= new Image();
	tab1_off.src 	= "images/nav/home_off.png";

	tab2_on 		= new Image();
	tab2_on.src 	= "images/nav/audio_on.png";
	tab2_off 		= new Image();
	tab2_off.src 	= "images/nav/audio_off.png";

	tab3_on 		= new Image();
	tab3_on.src 	= "images/nav/video_on.png";
	tab3_off 		= new Image();
	tab3_off.src 	= "images/nav/video_off.png";

	tab4_on 		= new Image();
	tab4_on.src 	= "images/nav/faq_on.png";
	tab4_off 		= new Image();
	tab4_off.src 	= "images/nav/faq_off.png";

	contact_us_on 		= new Image();
	contact_us_on.src    = "images/nav/contact-us_on.png";
	contact_us_off 		= new Image();
	contact_us_off.src   = "images/nav/contact-us_off.png";
}


function imgAct(imgName) 
{
	 document[imgName].src = eval(imgName + "_on.src");
}

function imgInact(imgName) 
{
	document[imgName].src = eval(imgName + "_off.src");
}