var bannerCount = 0;
var totalPos = 0;
var bannerHeight = 60;
var skipMove = true;
function switchSponsors(){
	if(totalPos == bannerHeight * (bannerCount-2)){
		if(skipMove){
			skipMove = false;
			return true;
		}
	}
	totalPos += bannerHeight;
	new Effect.Move('sponsors',{ x: 0, y: -bannerHeight, mode: "relative", duration: 1, 
		afterFinish: function(){				
			if(totalPos == (bannerCount-1)*bannerHeight){
				$('sponsors').setStyle({ top: '0px'});
				totalPos = 0;
				skipMove = true;
			}
		}
	});
}
Event.observe(window, 'load', function() {
	bannerCount = $('sponsors').select('.banner').length;
	new PeriodicalExecuter(switchSponsors, 2);
});