How windows activation works

If you buy or build a new comptuer, at some point you will need to activate windows XP or vista to continue using it. Microsoft introduced windows product activation (WPA) to many of its products as a way to prevent software piracy. When installing windows, you have up to 30 days to activate windows or you will not be able to login anymore. Activation is usually done online or by telephone. Remember that activation and windows registration are two different things so don’t confuse them. Registration is optional and activation is a must.

If you buy a PC from a vendor then it will come already activated unlike building your own or buying a computer without OS installed. So how does WPA work? The process starts with an installation ID. When activating windows through telephone, you are required to provide the installation ID or if you do it online then the computer will send the ID automatically. Installation ID is a number consisting of 50 decimal digits that are divided into groups of six digits each. This ID contains the 25 digit product ID which you entered when installing windows and the hardware information of your computer. When you provide Microsoft the installation ID when activating, they will generate and give you the activation code needed to activate windows. After activation, every time you start windows, it checks to make sure that your computer hardware information matches with the code. Windows checks for the following hardware changes:

Display Adapter
RAM Amount Range
Network Adapter
Processor type
Processor Serial Number
SCSI Adapter
IDE Adapter (Motherboard)
Hard drive
Hard Drive Volume Serial Number (VSN)
CD/DVD drives installed

Microsoft keeps a record of the information it collects on every licensed copy of windows XP/Vista so that no one can install it on another computer and activate it. So if you make too many changes to your hardware then you will be required to activate windows again. If you are just re-installing windows and you don’t want to activate again then you can backup a file called wpa.dbl found in the system32 folder then after installing windows, take the file you backed up and replace it with the one in the system32 folder.