How can you completely remove Windows 7 from a PC?

[AssaultRifle]

My laptop originally had Windows Vista Home Premium x86 on it, but I upgraded it to Windows 7 Ultimate x86. Is there any way to return to Windows Vista Home Premium?

PS: I don't want to do this, I'm just saving it as a last resort because of this registry problem I am having.

 

[richc46]

Two possible ways:

If you have the original DVD, you can reinstall

If the System came preinstalled there may be a recovery drive that will allow you to return to factory specs. This partition is sometimes rendered useless, however, on installation of new Systems.

If you are having a registry problem the easy solution is system restore or system image.

 

[Ztruker]

I have not tried this since I never upgrade, but MS thinks it's possible.

How to restore a computer to a previous Windows installation after you install Windows Vista
How to restore previous Windows installation after Windows 7 upgrade - Instant Fundas

 

[gregrocker]

As suggested, System Restore to before the registry problems, run sfc /scannow, then if necessary a http://www.sevenforums.com/tutorials/3413-repair-install.html?ltr=R which is the next best thing to reinstalling.

You do not need to restore to Vista to clean reinstall Win7. When you boot the Win7 DVD it will scan the HD to see another OS which is all that is needed to pass a flag allowing use of Upgrade version key, even if you then go on to use Custom>Drive tools to repartition and/or reformat.

If you feel you may have a virus, it is best to wipe the HD. Make your Recovery Disks first so you have a path back to Vista, then use this tutorial: http://www.sevenforums.com/tutorials/91339-ssd-hdd-optimize-windows-reinstallation.html

If you reinstall Win7 upgrade version to a wiped HD, you'll then need to use one of the workarounds here to activate since the booted installer will not see an OS to allow Upgrade key: http://www.sevenforums.com/tutorials/31402-clean-install-upgrade-windows-7-version.html