What is genuine Windows validation?
Validation is a short process that enables you to verify that your copy of Windows is genuine. If you request a genuine Windows download from the Microsoft Download Center, you will be prompted to complete the validation process. You may choose not to validate your Windows and still obtain your requested download. However, validating now will enable faster access to the Download Center in the future when validation may be required. After successful validation, a Microsoft Windows Download Key will be stored on your system for future use. Following the validation process, you'll be taken back to the initial download details page to obtain your requested download
Is Windows activation required?
The validation process also determines if you have activated your copy of Windows. If you have not activated Windows, you will be asked to enter the 25-character product key printed on the Certificate of Authenticity (COA) you received with your PC or software purchase. The product key protects your software from theft, as Windows cannot be activated without it. Windows activation is not required for genuine Windows validation. You may access genuine Windows downloads with either an activated Windows client, or by validating to receive a Microsoft Windows downlad key.
Among the products that validation are beeing used are:
Windows Media Player 10
Windows Media Player 9 Series for Windows Xp
Windows XP Video Decoder Checkup Utilit
Windows Messenger 4.7 for Windows XP
Microsoft Calculator Plus
Codec Installation Package for Windows Media Player 7.1 or later
Windows XP SP2 Deployment Tools for Advanced Users
Update for Background Intelligent Transfer Service
Windows XP SP2 Support Tools for Advanced Users
Photo Story (require validation)