function swapNav(div, what){
	var theDiv = document.getElementById(div);
	if (what == 'over'){
		theDiv.className = 'nav_link_over';
	} else {
		theDiv.className = 'nav_link';		
	}
}
function swapNav_purple(div, what){
	var theDiv = document.getElementById(div);
	if (what == 'over'){
		theDiv.className = 'nav_link_over_purple';
	} else {
		theDiv.className = 'nav_link_purple';		
	}
}