An unsupported version of Windows will no longer receive software updates from Windows Update. These include security updates that can help protect your PC from harmful viruses, spyware, and other malicious software, which can steal your personal information. Windows Update also installs the latest software updates to improve the reliability of Windows—new drivers for your hardware and more.

http://windows.microsoft.com/en-us/windows/help/what-does-end-of-support-mean

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