Expiration Date with a Notification

I’m currently using the Post Expirator plugin which when set a custom field is created with a key “expiration-date”. I’m not quite sure how the value works. If I set an expiration date of December 17, 2008 @ 11 it enters it like this: 1229529600

What I want to do is setup a cron job to check the expiration-date one week before and send an email to the post owner letting them know it will expire in a week.

But like I said I can’t figure out how to check 1229529600 to see if it’s one week before.

Any ideas??

or would it be easier to go two weeks out from the post-date and check that?