this code snippet works fine on its own but as soon as it's added to Magento it doesn't work. Anyone have any thoughts?

<!-- Start Edits -->
<script type="text/javascript" src="jquery.autocomplete.js"></script>
<script type="text/javascript" >
//<![CDATA[
var jQuery = jQuery.noConflict(); 
jQuery(document).ready(function()
        {
        jQuery("#antique_toys_materials").keyup(function() 
            {
                var tag = jQuery(this).val();
                if(tag != '')
                {
                    jQuery.ajax(
                    {
                        type: "GET",
                        url: "../../../../../../../../../../auto_suggest_original/autocomplete.php",
                        data: "q=" + tag,  
                        cache: true,
                        success: function(result)
                        {
                            jQuery("#antique_toys_materials").val(result);
                        }
                    }
                    );
                }
                return false; 
            }
        );
        }
    );
        //]]>
</script> 

Thanks!

Assuming you created a CMS Page already and name of that page is your_page_name this name should be included in if ($headBlock->getModuleName() == 'Mage_Page' && $headBlock->getTitle() =='your_page_name'):

Now add this code in your app/design/frontend/your_package/your_theme/template/page/html/head.phtml

You can read more at Magento extensions documentation