I currently am setting up a computer for a relative. I want to re-use his old computer if possible, but I am not sure how well it will perform with Windows 7 Professional 64 bit. I plan to buy Windows 7 Professional OEM and set the computer up. After setting it up I would like to hand it back and ask my relative to test it. I'm not sure how well it will perform, because right now it's really slow and unresponsive while running Windows XP, and tons of malware. If setting it up freshly does not help performance-wise, I would like to dump the computer and build a completely new one. Now, the question is:

Will I be able to re-use the Windows 7 Professional OEM version?

Apologies if this question seems noobish, I've never actually bought a Windows version, except the ones that come pre-installed, which, on the other hand, I never used.

  • Why don't you simply install Windows 7 with the generic key allowing you to verify the problem is solved?
    – Ramhound
    Mar 1 '14 at 14:31
  • Are you suggesting to use the 30-day trial? I didn't know it existed, sorry.
    – wondering
    Mar 1 '14 at 14:46

There is no problem if you install the windows version on the computer and do not activate it. YOu can still use it for 30 days, which should be more then enough to test if it runs fast enough on your hardware. If it does not, just wipe it from the old computer, buy new hardware and install it on that.

If you buy the 'normal' (not OEM) version then you are even allowed to install it, activate it and use it as long as you want. On any hardware, as long as it is on one machine at the same time.

E.g you could:

  • Install on computer 1, use it for a while,
  • Then buy a new computer. Wipe the OS from computer 1. Install on the new computer (#2), use it for a few years, ...
  • Buy even newer hardware (computer #3). Wipe computer #2, install it on computer #3, ...
  • etc etc

OEM versions of Windows 7 are identical to the normal full license retail versions except for the following:

  • OEM versions do not offer any free Microsoft direct support from Microsoft support personnel.
  • OEM licenses are tied to the very first computer you install and activate it on.
  • OEM versions allow all hardware upgrades except for an upgrade to a different model motherboard
  • OEM versions cannot be used to directly upgrade from an older Windows operating system


  • "Directly upgrading" is different from "installing from scratch", isn't it?
    – wondering
    Mar 1 '14 at 14:45
  • @wondering - Yes; You can use the generic key in either case.
    – Ramhound
    Mar 1 '14 at 14:55
  • "Directly upgrading" is installing the new OS while trying to keep as much from the old install as possible. Sometimes useful, but not on a machine which you describe as containing tons of malware. You want is a clean install, all updates, a virus scanner (and update that), and only then you should consider copying some of the old stuff back.
    – Hennes
    Mar 1 '14 at 14:59
  • @Hennes - Is the 'normal' version you mentioned the so-called 'MAR' version (Microsoft Authorized Retailer)? I decided to use the full version, but it seems incredibly hard to find the correct version. Thanks!
    – wondering
    Mar 2 '14 at 18:54

Usually one time. If you use it on a second computer which is offline all the time, it might work.

When I had an XP OEM I installed it at least on two computers and it worked for me. I didn't even had to put a key on it.

I don't know how the Windows 7 versions nowadays are.


An OEM Windows license is meant to be used only on a new computer, and it's tied to that computer only — you're not allowed to transfer the license to another computer.

However, Windows 7 has a 30-day "grace period" before you're required to "activate" the Windows installation, which is the step that links the product key to the hardware. You could probably install Windows on one computer, test it for up to 30 days without activating it, and then decide to either activate on that computer, or wipe it and install on a different computer instead.

Installing an OEM copy of Windows on an old computer, though, as a replacement for its preinstalled copy of Windows XP, probably violates the OEM license.

  • How would buying a software and installing it on any system violate the license? This doesn't make sense to me, because how dare they tell me where I install a software I paid money for?
    – wondering
    Mar 1 '14 at 14:44

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