function doSomething(x) {
	if (x=="nav_contact") c="current_contact"; 
	else if (x=="nav_home") c="current_home";
	else c="current";
	var y=document.getElementById('nav').className;
	if (y)	document.getElementById(y).className="nav";
	document.getElementById(x).className=c;
	document.getElementById('nav').className=x;
}