Regarding Windows 8.1, which would be good to update to, if you can figure out a way to, run the Windows Upgrade Assistant to tell you what might be preventing the upgrade. I found that an old scanner program wasn’t compatible with Windows 8.1 and had to uninstall it: http://windows.microsoft.com/en-US/windows-8/upgrade-to-windows-8
See item three “Can my PC run Windows 8.1”.