Howtogeek posted a tutorial about turning your Ubuntu PC into a LAMP web server

Got a Linux PC you want to put to work? Maybe you're not comfortable with the command-line only version of Ubuntu Server Edition. Here's how to keep the standard Ubuntu desktop and add web-serving capabilities to it.
Whether you're not comfortable with a command-line only system, you're using your Ubuntu desktop for other things, or you just need it installed for a few particular apps, you can add Apache, MySQL, and PHP to any standard desktop installation of Ubuntu very quickly and easily

  How to Turn Your Home Ubuntu PC Into a LAMP Web Server