What does "Operating System sold as an Upgrade" mean?

Most of our laptops and desktops are sold without an operating system. This means that you will get a machine that has a blank hard drive. We offer Windows XP – Home Edition and Windows XP – Professional Edition as an upgrade for an additional charge. If the upgrade is purchased, we will load the operating system onto the laptop or desktop and provide you with a valid license and the media for the operating system. Please refer to the "Frequently Asked Question" - "What Software comes on the Computers?" for further details.