How to override formatting for a CCK field? I have a CCK field called "stock". I dont want visitors of the website to see the value of "stock". I want them to see either "In Stock" if the value is more than 0, or out of stock if the value is less than zero.

Any idea how I can do that without actually editing the node display template?
Depending on the type of the field you are using, there are template files for those as well e.g. a number field (field--number-decimal.tpl.php). that way you would only have to override the field template, rather than the node template.