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Can't find exact same scenario on other Qs so posting this ....

Installed Windows 7 Ultimate from Dell OEM CD. Did not activate and using 30 day period.

Can I just change key in setting IF: 1- I buy Professional OEM CD (from tigerdirect/online etc.? 2- I buy Ultimate OEM CD (from tigerdirect/online etc.?

Simply don't want to reinstall and move to professional ver. thx.

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so basically you're looking to do a "Anytime Downgrade". – KronoS Sep 23 '11 at 18:22
You can't use the OEM version you buy from TigerDirect on that Dell laptop, unless you're Dell. OEM = Original Equipment Manufacturer. – Mar 31 '13 at 22:17
up vote 6 down vote accepted

You cannot downgrade to Windows 7 Pro without doing a complete re-installation, and you cannot use a Windows 7 Pro activation key to activate Windows 7 Ultimate. However, you should be able to use the activation key from an OEM copy of Windows Ultimate that you purchase.

If it doesn't accept the Win7 Ultimate activation key when you enter it, you should be able to do a repair installation of Windows using the Ultimate OEM CD that you purchased and use that OEM CD's activation key. It will activate Windoows 7 Ultimate using the OEM CD, but it should not remove any of your files or software.

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You can downgrade Windows 7 ultimate to pro, check this link: UnaWave - Installation - Downgrade

A Windows 7 Ultimate Installation can normally not change into a minor version of "Windows 7 Home Premium" or "Professional". If you have installed a preview version of Windows 7 Ultimate (e.g. beta, release candidate build 7100 or RTM build 7600) and want to install a cheaper version Windows 7 Home Premium or Professional the installation is refused:

But with a change of a registry key whilst installation you can fake a minor version - so you can install the minor version

Change these registry keys ...

... into these for installing Windows 7 Professional ...

... or into these for installing Windows 7 Home Premium:

A re-boot after change of these registry keys is not necessary.

The version name to be entered must be identical to the version name on the installation DVD. See here the differences of an English and a German installation:

For downgrading do not boot from Windows 7 installation DVD.

 Boot to Windows 7 and start "Setup.exe" from DVD; or after loading DVD the setup process starts automatically.
Start Upgrading (even this sounds absurd):

After successfully downgrading the welcome screen shows the new version:

Also the program "winver" shows the successfully downgrading:

All data, documents, music and movie files, installed driver and programs, shortcuts, program and user settings are retained. Only in a few Windows 7 programs some settings are reset to the initial settings; e.g. in the "services". After the downgrade the Windows 7 installation, of course, must be re-activated.

Attention: In Windows 7 Ultimate Build 7100 (Release Candidate) the effort is greater. First the entire DVD content must be copied to a folder to the hard drive. Then open in subfolder "sources" the file "cversion.ini" and change the entry "MinClient=7233.0" to "MinClient=7077.0". Then you can start the installation with "Setup.exe" (one folders hierarchy up). After the installation the entire folder can be deleted.

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Nice hack...... – Joe Taylor Feb 2 '12 at 9:36
Please include the gist of the linked web page in your answer, otherwise it'll become useless once the web page is removed. – Daniel Beck Feb 2 '12 at 17:21

Can't be done. When you install Windows 7, it installs THAT edition. You can't go backwards. If you use a multi-disk with all the installations, it asks you during Setup, and tells you to make sure you chose the right one. You will need to reinstall Windows 7 Pro to get only the Pro features. If you already have OEM Ultimate, I'd say keep using it (unless it was pirated)

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I was in a similar situation. I had "Windows 7 Home Prem OA HP" on a HP desktop I bought new and then upgraded the system to Ultimate with an Upgrade key. But now that I bought a refurb desktop with no OS (with a COA for "Windows Vista Business OEMAc") I needed to use that Ultimate license on the "new" refurb desktop. So my "downgrade ultimate to home premium" search brought me here, amongst other places.

I used the registry solution explained here, manually and without the use of a popular tool from a website called deviantart. I figured I was better off hacking the puter manually myself. I did however used it this way (notice upper & lower case matching the "Ultimate" entry format):

HKLM\Software\Microsot\Windows NT\CurrentVersion EditionID "Ultimate" changed to "HomePremium" ProductName "Windows 7 Ultimate" changed to "Windows 7 HomePremium"

For reference, I also used the following posting on tomshardware (, specially the response by aquasystems.

Then, I needed to do the "in-place repair upgrade." I tried using the windows 7 repair disk I had originally made with the HP desktop only to realize that it was not what I needed. What I needed was a Windows 7 Home Premium 64-bit installation disk. Since I was afraid to use the system recovery disks of the hp desktop (who knows, it might have worked but I did not want to risk a complete recovery), I downloaded an iso image from digitalriver. For that I followed the advice and links I found on a microsoft community post (:// I burned the iso image to a dvd using imgburn.

To do the "in-place repair upgrade" I used the DVD I had made, pop it into the dvd drive and allowed autorun to start the process (you can navigate to the dvd and double click setup.exe if necessary). I then followed the process as presented by unawave ( and here, although the german screen shot is just superfluous. This was a very good step by step site that helped me. I did not get a compatability report about the languages pack; only a small warning that the system needed rebooting before runing setup.exe (which I did before running setup.exe a second time). After the second time running setup.exe, then the rest of the process went as planned. When I was done, I was able to confirm that the windows version had been downgraded to Home Premium.

But, a brief warning about activation of the product key. Once I "downgraded" I needed to re-activate my Home Premium key (stuck on the side of the HP desktop). When I tried activating it, the system responded that it was invalid and that I could not activate it online and needed to do a phone activation process to get an confirmation id. I figured, I was already done with the deed and since I legally owned the license (aka product key) I had nothing to loose. The pop-up warning window asked me to call a toll free number and follow instructions. The call was answered by an automated system which asked me to enter on the phone a total of nine six-digit number groups which were displayed on the pop-up instructions. After this, the automated response indicated that my activation was valid and that I needed to enter eight six-digit number groups (A through H) it would give me to put in their corresponding spaces on the pop-up instructions window (see :// The automated system allows for all the number groups to be repeated to verify they are entered correctly. I completed the phone verification process and there it was ... the install was activated and fully functioning as it used to be. So, this was a successful "in-place repair upgrade" downgrade from Windows 7 Ultimate to Windows 7 Home Premium (HP original install).

My thanks go to everyone who contributed in this thread on this page. Also, my thanks go to the following websites and postings which also helped me to do this. Mind you, I used the advice in all of them as advice only and did not follow anyone's instructions blindly or uniquely. Always do your homework before undertaking tinkering such as this ... and of course, always backup backup backup






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Choose Run and write regedit.

Go to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion

Change the keys EditionID and ProductName.

EditionID can be found in your Windows 7 installation CD under sources\ei.cfg.

ProductName will be shown when you try to install and are denied:

Windows 7 Ultimate cannot be upgraded to Windows 7 Home Premium

Here the Windows 7 Home Premium is the ProductName.

Make sure that it matches exactly.

This procedure worked like a charm for me!

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protected by Community Dec 13 '15 at 16:11

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