document.onkeydown = NavigateThrough;

function NavigateThrough(event){
	if( !document.getElementById ) return;
	if( window.event ) event = window.event;
	var link = null;
	var href = null;
	switch( event.keyCode ? event.keyCode : event.which ? event.which : null ){
		case 0x25:
			link = document.getElementById ('NextLink');
			break;
		case 0x27:
			link = document.getElementById ('PrevLink');
			break;
	}
	if (link && link.href) document.location = link.href;
	if (href) document.location = href;
}