Windows 8 activation error 0xC004F061 - causes & solutions

Error description: "The Software Licensing Service determined that this specified product key can only be used for upgrading, not for clean installations."

If you're getting this error code, it either means:

1. You purchased a Win8 upgrade instead of the full OEM/System Builder version needed for clean installs on new machines. If you did this, go return it and get yourself the right version. E.g., Win 8 Pro 64-bit: http://www.amazon.com/Windows-Professional-System-Builder-64-Bit/dp/B0094NXBZ0/r ef=sr_1_2?ie=UTF8&qid=1365894007&sr=8-2&keywords=win+8+system+builder (there's also the non-Pro edition; just make sure it says "OEM" or "System Builder" to make sure you're not getting an upgrade-only license). You can also get it from brick and mortar retailers like Staples or Office Depot, but make sure you're getting the OEM/System Builder version, not the upgrade.
2. Or, perhaps, you did (1), figured out what you did wrong, have now returned the Win8 upgrade and purchased the OEM/System Builder version, but still get the above activation error (even despite completely starting over - using BootCamp Assistant to remove Windows and starting over from scratch).

These steps solved (2) for me:

- Mouse down to bottom left corner of desktop (the little Start quad will pop up), right click, go to Command Prompt (Admin).

- Type regedit.

- Drill down into HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/ and change MediaBootInstall to 0.

- Exit regedit.

- Reset the licensing status of your machine by running the following in the command window: slmgr /rearm

- Reboot.

- In my case, after rebooting, my system was already showing as licensed with the product key that had given me the above error repeatedly before. You can check activation status in Control Panel > System and Security > System, or Charms (top right corner hover until vertical menu bar slides out) > Settings > PC info.

I'm not an expert, but these steps worked for me, so I'm spreading them here in hopes that it will save someone else the wasted time & frustration.