I want to display a product that is sold out, but without having my customers still be able to buy

I have another problem since I updated to the newest marketpress installation.

I am trying to make products that are out of stock visible, but not purchaseblae by customers. right now when I zero out inventory, it still allows people to go through the purchase process. this is very problematic. I would likke to be able to have an out of stock logo like you use to have.

how can I do this?