Web Crawler

OK, I have a single page web crawler script written in php, which doesn't work, to be honest i can't remember where it cam from, but what i need it to do is automatically crawl the internet, looking for websites with a particular piece of code in, for example a competitors analytical tracking code, once it finds this code in a page it sends the URL of the page to a mysql database and moves on, so for example if it finds multiple pages on one domain with the code in, it only needs to record it once. The end result is i basically want a list of websites who use my competitors tracking system. I have included the page of code i have and to the succesful bidder i will provide the information that i want to be tracked This code is just an example if this code can work then perfect if you need to start again not a problem. In your bid please tell me your approach, so i uget that you understand the project. I will also supply the details of the mysql database. This code needs to be able to simply run around the internet on it's own and search pages continuously without any assistance or intervention from me.