- Install Windows retail SKU, but do not activate it. You can borrow disk or download ISO for this. - Start installing upgrade version, then reformat partition, supplying upgrade key in the process.
At the end, you will have Windows upgrade installed and activated, fully functional.
For Windows 7, if you have machine with empty disk, then you start installation of upgrade version, but do not provide product key and uncheck 'Activate' checkbox. This will install Windows in trial mode. Then, start upgrade setup again and let it 'upgrade' OS... After that, you have activated Windows on the machine.
For Windows 8, I am not sure if process of double installation will work.