it is a cron job, a scheduled task the server will do whenever you tell it to, i have one setup on a server that converts .dbf's that are ftp'd into the webserver to mysql tables every fifteen minutes, to do this with a php page, you need to get the lynx browser and use that in your cron job to run the php page in the background, go to yahoo, and search for "run php page with cron" and you will find some nice tut's to help you