N editions of Windows 7 were created due to an EU rule requiring that Microsoft make available versions of Windows without Windows Media technologies. Although most of the Windows Media components can be manually added later by the user, some DRM components will not install, resulting in digital cable activation failing. This will result in the inability to record or watch copy-protected content.
There is no workaround for this issue. The PC will need to have the OS completely reinstalled using a non-N edition. The N editions were only offered for sale in Europe, although they are also available to MSDN subscribers. Those who purchased the N edition of the OS retail, or purchased a computer with it preinstalled, would need to purchase a new copy of Windows and reinstall with that. MSDN subscribers should simply download a non-N edition and reinstall with that.
