function change_color(tab_name) {
	var tab_name_array = new Array('index', 'profile', 'service', 'portfolio', 'contact', 'news', 'whats_new');
	var count = tab_name_array.length;

	for (var i=0; i<count; i++)
	{
		document.getElementById(tab_name_array[i]).className = "graytab";
	}
	document.getElementById(tab_name).className = "orangetab"; 
}