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I'm planning to buy a Windows 8 Upgrade for my computer, and need to know if I have to keep my Windows 7 disks around and have to install Windows 7 first before doing the upgrade, or if there is somewhere that I can enter my Windows 7 key alongside the Windows 8 Upgrade key if I want to do a clean installation of Windows 8 from bootable media.

Can I get by with just writing both keys on the disk like I have in the past?

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Previously covered by the answer here, the answer (and esp. the source) here etc. IMO the price difference between the Upgrade and System Builder versions wouldn't make sense if all that was different was an extra key entry screen in the former. – Karan Oct 26 '12 at 20:35
up vote 2 down vote accepted

You can install the upgrade without previous OS installed:

You just need to make a Windows 8 Pro upgrade install media and then boot from this disc and install the system (classic windows install procedure). If you get an error when activating (0xc004f061) then call MS support and they will help you to activate the system (you will need previous OS product key and the new Windows 8 PK).

How to create Windows 8 Pro upgrade install media? Download the Upgrade Assistant from and then run it on a Windows 7 or Windows Vista computer (Windows XP won't work). In the wizard select "install by creating media". It will download the files and then create and ISO file. Burn this file on DVD and you'r done.

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It says here that you must be running Windows XP SP3, Windows Vista, or Windows 7 to upgrade to Windows 8.

enter image description here

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"They won't need to reinstall the previous version to do the upgrade; they can just upgrade on top of the Release Preview," Microsoft said. How does it work in this scenario? – Darth Android Oct 26 '12 at 22:43
The last post on this page says The upgrade replaces the old license completely. I guess that you'll have to provide your old license key and you either get a new key or the old key is 'converted' to a win8 key. – page4096 Oct 26 '12 at 23:02
@page4096 - Its not actually replaced, if the upgrade is removed, the old license can then be used on that machine. – Ramhound Nov 13 '12 at 15:22

You must have the previous version of Windows installed. If you don't want to install it, you can instead purchase the System Builder version of Windows 8 Professional for $139.99 or $99.99 for regular.

Whether or not you need the disks themselves is a different thing, you can usually download a copy of old operating systems from Microsoft. But you will need the license key, and have the previous version of Windows installed, to use the upgrade versions of Windows 8.

Source: I've installed the RTM version multiple times, being a developer.

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If you have OEM or FPP Windows you can NOT download install media from MS. (Download possible only for MSDN, Volume License etc. - won't work for OEM or FPP Product key) – dimitrij Jan 30 '13 at 11:24

It can be done both ways... specially with Windows 8, where in you can chose to just perform an upgrade operation or perform clean install by choosing keep nothing which would be almost like clean install. All you need is the product key and media to install from.

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You should be ok with only your Win8 keys. After the upgrade, you won't be able to go back to Win7, unless you are doing a clean install of Win 7. Rather, you could create a Win8 recovery disk, which you should use if at all you need to re-install the OS for your system.

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To use the upgrade you must have Windows XP SP3, Windows Vista, or Windows 7 already installed. This means that the upgrade is useless for a machine that has no OS at all.

However once the installer verifies the previous OS is there, you can choose to run a clean installation (format the drive and install a fresh OS). Furthermore once windows 8 is installed you can re install it entirely at any point in the future without the old disk, as there is a built in "refresh" feature.

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