You can get image and thumbnail¬† image url using helper Mage::helper(‘catalog/image’) and also you can get thumbnail, full image and resize this image as your requirements. Here below is the code.

$productcollection = Mage::getModel('catalog/product')
->getCollection()
->addAttributeToSort('created_at', 'DESC')
->load();
foreach ($productcollection as $product){
$fullimagepath = Mage::helper('catalog/image')->init($product, 'image')->resize(800);
$thumb_imagepath = Mage::helper('catalog/image')->init($product, 'thumbnail')->resize(50);
}