GitHub for Windows now requires Windows Vista or later (including Windows 7, Windows 8/8.1, and Windows Server 2010/2012). If you are still using GitHub for Windows on an earlier version, you'll need to upgrade your operating system to get these updates.
Why do I need to upgrade my OS?
Many new features in GitHub for Windows require .NET Framework 4.5 or higher. Unfortunately, .NET 4.5 isn't compatible with Windows XP or Server 2003, so we can no longer support those platforms.
What if I continue to use Windows XP or Windows Server 2003?
Your current version of GitHub for Windows will still continue to work as-is, but will no longer receive updates and GitHub Support may have more trouble assisting you. You also won't be able to install the application on another XP machine or on your own machine if you uninstall it.