Call PHP code after checkout

First of all, if this thread is OT feel free to move it.

I am looking for a hook for Zen Cart to call a PHP module after the user has checked out. The hook should pass some kind of user ID, the item numbers, quantity and if they have been paid. We will be using this hook to integrate some event registration systems for a Boy Scout council.

Frankly, I am a decent PHP coder, but need this functionality pretty quick and I do not know where the heck to start with Zen. If this is actually a no-brainer, I would be happy to donate some beer money for being pointed in the right direction. I also have a small budget to have this coding done.

Thanks,
Andy Otto
-Andy-

All of the order information is in the database- Can you be more specific as to where you need to send the information?