function rollover()
{
	if(! document.getElementById || ! document.createTextNode)
		return;
	
	var n = document.getElementById('nav');
	if (! n)
		return;
	
	var tds = n.getElementsByTagName('td');

	for (var i = 0; i < tds.length; i++)
	{
		tds[i].onmouseover = function()
		{ 
			if (this.className == 'tab_outter')
			{
				this.className 				 				= 'tab_outter_hover'; 
				this.getElementsByTagName('div')[0].className	= 'tab_inner_hover';
			}
		}
		
		tds[i].onmouseout = function()
		{ 
			if (this.className == 'tab_outter_hover')
			{
				this.className 								= 'tab_outter'; 
				this.getElementsByTagName('div')[0].className	= 'tab_inner';
			}
		}
	}
}