Show thumbnail image without pop-up window

Locate media.phtml inapp/design/frontend/default/themename/template/catalog/product/view, and near line# 59, you should see:

<a href=”#” onclick=”popWin(’<?php echo $this->getGalleryUrl($_image) ?>’, ‘gallery’, ‘width=300,height=300,left=50,top=50,location=no,status=yes,scrollbars=yes,resizable=yes’); return false;”><img src=”<?php echo $this->helper(’catalog/image’)->init($this->getProduct(), ‘thumbnail’, $_image->getFile())->resize(120); ?>” alt=”<?php echo $this->htmlEscape($_image->getLabel()) ?>” title=”<?php echo $this->htmlEscape($_image->getLabel()) ?>” /></a>

change the part in red to the following:

<a href=”<?php echo $this->helper(’catalog/image’)->init($this->getProduct(), ‘image’, $_image->getFile()); ?>” title=”<?php echo $_product->getName();?>” onclick=”$(’image’).src = this.href; return false;”>

You should be able to modify it a bit more if you want the image to update on mouseover.