How would I set a t ime out on an auction product

hi

i have created an auction product object which has a closing date stating when the auction should close. I would like the product status to be closed, in the product list, when the closing date arrives.

please could you give me some code which would allow me to set up a timer on the auction product object, so that its status would change to closed when the closing date arrives. The object contains a variable 'status' which can be set to open or closed.

thanks