function preload_images(){
	//preload rollover images
	if (document.images) {
		sub_home_grey = new Image(46,14); 
		sub_home_grey.src="images/sub_home_grey.jpg";
		sub_about_grey = new Image(68,14); 
		sub_about_grey.src="images/sub_about_grey.jpg";
		sub_think_grey = new Image(108,14); 
		sub_think_grey.src="images/sub_think_grey.jpg";
		sub_services_grey = new Image(62,14); 
		sub_services_grey.src="images/sub_services_grey.jpg";
		sub_portfolio_grey = new Image(63,14); 
		sub_portfolio_grey.src="images/sub_portfolio_grey.jpg";
		sub_clients_grey = new Image(53,14); 
		sub_clients_grey.src="images/sub_clients_grey.jpg"; 
		sub_contact_grey = new Image(56,14); 
		sub_contact_grey.src="images/sub_contact_grey.jpg"; 
	}
}