var settings = [
	{
		selector : '#foo',
		scrollSpeed : '100',
		width : '2500'
	},
	{
		selector : '#bar',
		scrollSpeed : '200',
		width : '3500'
	}
];

var step = 1;
var headerWidth = $('html').width();

$.each(settings, function(index, c) {
	var restartPosition = c.width - headerWidth;
	var current = 0;

	setInterval(function() {
		var current = current - step;
		if (restartPosition == current) {
			current = 0;
		}
		$(c.selector).css('backgroundPosition', current +  'px 0');
	}, c.scrollSpeed);
});