Since it is a “free upgrade”, I will explore it. Hopefully it will be possible to just clone the primary drive and then upgrade the cloned drive. That way all that will have to be done to go back will be to swap the original primary drive back in. I am not that fond of “cloud” computing.
Use Macrium Reflect at http://www.macrium.com/reflectfree.aspx
This is disk imaging software. You can create Macrium Reflect boot CD, boot your PC from Macrium CD, plug in USB hard drive and create an image of your drive.
After you trash your PC, just boot your PC from Macrium CD, plug in USB drive again and this time restore the image back on to your drive.
Before you use Macrium on your PC, it’s best to test and learn this software on an old PC that does not have any useful stuff.
I hope this helps.