function prepare_slider(img_width, viewWindow){

    var x_pos = 0;
    var li_items_n = 0;
    var right_clicks = 0;
    var left_clicks = 0;
    
    var li_col = $('slider_list').getElements('li');
    
    li_col.each(function(li, index){
        x_pos += img_width;
        li_items_n++;
    })
    
    right_clicks = li_items_n - viewWindow;
    total_clicks = li_items_n - viewWindow;
    
    $('slider_list').setStyle('position', 'relative');
    $('slider_list').setStyle('left', '0px');
    $('slider_list').setStyle('width', x_pos + 'px');
	
	var log = $('log'); 
	
    var myFx = $('slider_list').effects({duration: 600, wait: true}); 
   /* var myFx = new Fx.Styles($('slider_list'), {
        duration: 400,
		wait: true
    });
    */
    var is_playing = false;
    
    $('left_but').addEvent('click', function(){
        if (!is_playing) {
			is_playing = true;
            cur_offset = $('slider_list').getStyle('left').toInt();
            if (left_clicks > 0) {
                myFx.start({'left': (cur_offset + img_width) + 'px'}).chain(function(){is_playing = false; });
                right_clicks++;
                left_clicks--;
            }
            else {
                myFx.start({'left': (-img_width * total_clicks) + 'px'}).chain(function(){is_playing = false;});
                right_clicks = 0;
                left_clicks = total_clicks;
            }
        }
    });
    
    $('right_but').addEvent('click', function(){
        if (!is_playing) {
			is_playing = true;
            cur_offset = $('slider_list').getStyle('left').toInt();
            
            if (right_clicks > 0) {
                myFx.start({'left': (cur_offset - img_width) + 'px'}).chain(function(){is_playing = false;});
                right_clicks--;
                left_clicks++;
            }
            else {
                myFx.start({'left': 0 + 'px'}).chain(function(){is_playing = false;});
                left_clicks = 0;
                right_clicks = total_clicks;
            }
            
        }
    });
    
}