The two different downloads allow you to have the "Add to Cart" button for 0 priced products enabled or disabled. The enabled "Add to Cart" button stays the same as it is in OpenCart, and disabled "Add to Cart" button becomes gray, so costumers can't add that product into the cart, as you can see from the pictures.
Installation is as simple as it can be, just open this, find that, after that add this, and it's done. No files are overwritten, no complicated database queries, no trouble at all.
If you need any help, free installation is on its way. Just contact me by leaving a comment, or via forum's PM (GoGo OpenCart).
OpenCart versions supported: All 1.5.1.x (see the notice at the bottom)
Extension's page: http://www.opencart.com/index.php?route ... on_id=4067
NOTICE: As soon as I test it with other versions of OpenCart, I will update the compatibility list, so stay tuned
