My Windows 8 machine was not getting updates from our Windows Update Services server.
When I looked at my computer account it showed the operating system as Windows XP x64 which is definitely wrong.

I found the following instructions on Microsoft’s Technet site:

ReInstall KB2734608 (found here, scroll down towards the bottom for the actual download)
Open an elevated Command Prompt
net stop wuauserv
rd /s %windir%\softwaredistribution
Use regedit to delete HKLM\Software\Microsoft\Windows\CurrentVersion\WindowsUpdate
net start wuauserv

This fixed my issue and my Windows 8 machines now report as having Windows 8 as their operating system and they immediately found updates that needed installed.