16.7. Windows Activation
Microsoft always intended for people to buy a separate copy of Windows for every PC they owned. But since those intentions lay hidden in the fine print of a thick licensing agreement, many people ignored them. Instead, they'd upgrade their desktop PC with Windows, and then slip that same Windows Upgrade CD into their laptop as well.
With Windows XP, Microsoft carries a much bigger stick than a vague licensing agreement. It comes in the form of copy protection, also known as Windows Product Activation (WPA).
As soon as you install Windows XP onto any PC, a 30-day clock begins ticking. Before those 30 days expire, you must click the "Click here to activate now" button as it rises over your taskbar's clock. When you click the button, Windows jumps into copy protection mode: Windows takes the 25-character Product Key (those individualized numbers printed on every Windows XP CD box), creates another 25-character key containing some details about your PC's hardware, and stores them both as a new, 50-character key in a secret file on your PC. Windows also sends all that information over the Internet to Microsoft's database.
Whenever you subsequently turn on your PC, Windows XP compares your PC's current equipment with the equipment listed in the key stored on your hard drive. If they match, you never know all this activity took place. If they don't match, Windows XP assumes it's now running on a different PC and a new clock begins ticking. You have three days to call Microsoft and explain what happened , usually that you've upgraded your PC with a substantial number of new parts .
And for those three poor souls who lack an Internet connection? Clicking the activation button provides them with a toll-free number to call Microsoft's activation police. After explaining their lack of an Internet connection, and reading Microsoft the contents of their "key"all 50 characters of itMicrosoft reads back a 42digit number that must be typed into Windows XPwithout typos. That's rightyou're exchanging 92 characters over the phone, something terrifying to those who hate reading a 16-character credit card number to have a pizza delivered.
Not every PC owner faces the activation process. PCs sold with Windows XP preinstalled come with a preactivated, OEM (Original Equipment Manufacturer) version of Windows XP: you don't need to click any buttons or read any numbers over the phone. And large corporations can distribute preactivated, "volume licensed" copies of Windows XP, saving their 3,543 employees from activating their PCs.
Note: If your copy of Windows XP isn't activated, Windows Update (see Section 15.3) may refuse to install the latest patches and Service Packs.