function swap(action, amount){
	if(typeof amount == "undefined"){
		amount = 281;
	}
	
	
	speed = 500;
	tot_height = $('#img_roll').height();
	if(typeof nextPos == "undefined"){
		nextPos = 0;
	}
	
	if(action == "prev"){
		nextPos += amount;
		if(nextPos > 0){
			nextPos = (tot_height-(tot_height*2))+amount;
		}
	}
	else{
		nextPos -= amount;
		if(nextPos < (tot_height-(tot_height*2))+amount){
			nextPos = 0;
		}
	}

	
	$("#img_roll").fadeTo(speed,0,function() {
		$("#img_roll").css( {
			position: 'relative',
			top: nextPos
		});
	}).fadeTo(speed,1);
	
}