How to list all special price products according the category

Hi all,
I have a part in my project that i have to show all special price products in a page for different category and i have done it. It\’s very simple just go to your admin and create a static page \"Sale\". Now add

{{block type=\"catalog/product_list\" name=\"home.catalog.product.list\" alias=\"product_homepage\" template=\"catalog/product/sale.phtml\"}}

and save the page.
after that go to your app\\code\\core\\Mage\\Catalog\\Block\\Product and create a file sale.phtml and pest the following code in to your file and run it. 

<?php if(Mage::app()->getRequest()->getParam(\'category_id\')==\'\'){ ?><h2 class=\"subtitle\"><?php echo $this->__(\'Sale\') ?></h2><?php
    $category_model = Mage::getModel(\'catalog/category\'); //get category model
    $_category = $category_model->load(2);  

//$categoryid for which the child categories to be found    
    $all_child_categories = $category_model->getResource()

->getAllChildren($_category);
   
    foreach($all_child_categories as $category)
        {
            if($category!=2){
                $cur_category = Mage::getModel(\'catalog/category\')->load($category);
                if($cur_category->getIsActive()){  ?>
                    <a href=\"<?php echo $this->getBaseUrl(\'all-new-arrival\').\'sale/?category_id=\'.$category; ?>\"><img src=\"<?php echo $cur_category->getImageUrl(); ?>\" />

<div><?php echo $cur_category->getName(); ?></div></a>                   
            <?php    }
            }
        }
?>   
<?php }else{ ?>

<?php
    $todayDate  = Mage::app()->getLocale()->date(

)->toString(Varien_Date::DATETIME_INTERNAL_FORMAT);
    $categoryId = Mage::app()->getRequest()->getParam(\'category_id\');
    $catagory_model = Mage::getModel(\'catalog/category\')->load($categoryId); //where $category_id is the id of the category
    $collection = Mage::getResourceModel(\'catalog/product_collection\');
    $collection->addCategoryFilter($catagory_model); //category filter
    $collection->addAttributeToFilter(\'status\',1); //only enabled product
    $collection->addAttributeToFilter(\'special_from_date\', 

      array(\'date\' => true, \'to\' => $todayDate))
       ->addAttributeToFilter(\'special_to_date\', array(\'or\'=> 

        array( 0 => array(\'date\' => true, \'from\' => $todayDate),
                    1 => array(\'is\' => new Zend_Db_Expr(\'null\')))
                ), \'left\');
    $collection->addAttributeToSelect(array(\'name\',\'url\',\'small_image\',\'price\',\'special_price\')); //add product attribute to be fetched
         
    $collection->addStoreFilter();   
    if(!empty($collection))
    { ?>
    <div class=\"category_products\">
      <?php  foreach ($collection as $_product):  ?>
          <div class=\"product\">
            <a href=\"<?php echo $_product->getProductUrl(); ?>\">
            <img src=\"<?php echo $this->helper(\'catalog/image\')->init($_product, \'small_image\')->resize(172,235); ?>\" width=\"172\" height=\"235\" />
            <div class=\"product-name\">
                <a href=\"<?php echo $_product->getProductUrl() ?>\" >
                <?php echo substr($_product->getName(),0,40).\' ...\' ?> 
                </a>
            </div><br/>
            <div class=\"price\">
            <?php echo $this->getPriceHtml($_product, true) ?>
            </div>           
            </a>
         </div>  
      <?php endforeach;   ?>
     </div>      
 <?php   }else{ ?>          
        <p class=\"note-msg\"><?php echo \'No products exists\';  ?>  </p>
 <?php   }  ?>
<?php } ?>