Triggering a PHP Script

My Problem: I've got a PHP script (running on Apache) that can take several hours to complete. The script sends out a newsletter to those who have requested it. When calling this script from a web browser, the browser hangs until the script has fully executed. If the user hits "Stop" while the script is running, it will terminate the script. My Questions: What is the best way to trigger this script? Is there a way to do it without using a CGI script? I am basically wondering if there is a way to create a "trigger this php page" script that will run the script on Apache and not hang the browser. Also, are there any problems calling MySQL from a PHP CGI script? Thanks, Ryan Bates