Can any1 advise me if and/or how I can do the following?

We have a list of used cars that we manipulate using Excel to give a clean list of current stock throughout our group. This list is then uploaded to our website. We want to have images associated to the cars on list using the reg as an id key. We need a way of automating the maintenance of the image files so that when a car is sold we can delete the relevant image from our central directory. The way I imagine it is something to look at the image files and compare the reg to the list. If the reg is not in the list then it would delete the image file. We don't host our website so we have to send the stocklist and image files on a daily basis. I hope this is clear...I appologise if it's not.

Cheers...