To upgrade to Windows 8.1 via the store see here:
Unfortunately its quite buggy so see here for a solution of the update not appearing in the store:
Once you have Windows 8.1 ensure you install Windows 8.1 Update 1:
Thank you, it was helpful. I had no update 2871389 installed, and it turned out that I do need it to be installed in the first place ( http://support.microsoft.com/kb/2871389 ) to see the Windows 8.1 update in the Store.
In addition, I run the Windows Update Troubleshooter (http://support.microsoft.com/gp/windows-update-issues ), and it found several corrupted registry entries and other issues related to the Windows Update subsystem.
After I installed the update, run the Troubleshooter tool, and rebooted the notebook, Windows 8.1 update appeared in the Windows Store.
An additional link that might be helpful to those unfortunate souls who has the same issue: http://download.microsoft.com/download/E/2/A/E2ABDAF3-5414-47CB-9AD2-5E31A10B2704/winupcompat.diagca... This tool search the PC for problems preventing it wrom being upgraded to Windows 8.1.
I wonder what was the cause for the registry corruption. This is a brand-new notebook. Yesterday I turned it on for the first time.