Ad Checker

This should be a fairly simple script for anyone who knows how to scrape content from other websites. This would be perfectly legal. The overall concept: The script should verify that ads on remote websites are still active. It makes regular checks, and puts an alert up when one is not. So basically, this is a two part system. Part #1: I add two URL's to a MySQL table. One for the site I am advertising, and one for the site that I am advertising on. Part #2: The script uses a cron job (once per day or so) that verifies whether the ad is up or not. It does this by scraping the content, then runing a regular expression to see if that URL exists on that page. If it does, then in the MySQL database set the result field? to "1". If it does not exist, set it to "2".