//Thank you to Derek Allard for writing this elegant little script - www.derekallard.com

window.onscroll = function()
{
	if( window.XMLHttpRequest ) { // IE 6 doesn't implement position fixed nicely...
		if (document.documentElement.scrollTop > 240) {
			$('navContainer').style.position = 'fixed'; 
			$('navContainer').style.top = '0';
		} else {
			$('navContainer').style.position = 'absolute'; 
			$('navContainer').style.top = 'auto';
		}
	}
}