I recently bought a system online which came with Windows 8 Professional 64bit, as soon as the system arrived I formatted it and installed Windows 7 Ultimate, the windows 8 dvd was unopened so would I be able to sell the copy of windows 8 with the key provided??
If it is an OEM copy of Windows 8 with the OEM sticker and key on the system, then NO you can not legally sell the license. I believe if it is an unused retail copy you can. I am assuming it is OEM if it came with a new system. Retail copies of windows are typically pretty expensive.