if (document.images) {

	img1on = new Image();           
	img1on.src = "images/btn_services_b.gif";  
	img2on = new Image();           
	img2on.src = "images/btn_products_b.gif";  
	img3on = new Image();           
	img3on.src = "images/btn_portfolio_b.gif";  
	img4on = new Image();           
	img4on.src = "images/btn_contact_b.gif"; 
	img5on = new Image();           
	img5on.src = "images/btn_company_b.gif";
	img6on = new Image();           
	img6on.src = "images/btn_home_b.gif";

 
	img1off = new Image();          
	img1off.src = "images/btn_services_a.gif"; 
	img2off = new Image();          
	img2off.src = "images/btn_products_a.gif"; 
	img3off = new Image();          
	img3off.src = "images/btn_portfolio_a.gif"; 
	img4off = new Image();          
	img4off.src = "images/btn_contact_a.gif";
	img5off = new Image();          
	img5off.src = "images/btn_company_a.gif";
	img6off = new Image();          
	img6off.src = "images/btn_home_a.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");
	}
}