Windows Vista Upgrade versions requires a previous version of Windows to be installed on a system, before using. This may cause problems if your system is badly damaged by malware, or if you just want to perform a clean installation. You don't need a previous version of Windows to perform a "clean install" using a Windows Vista upgrade disk. It's a tedious workaround, requiring Vista to be installed twice, but it's easy.

Perform these simple steps to perform a clean install of Vista without a previous version of Windows installed with an upgrade DVD:

1. Boot from the Windows Vista Upgrade DVD and start the setup program.
2. When prompted to enter your product key, DO NOT enter it. Click "Next" and proceed with setup. This will install Windows Vista as a 30-day trial.
   
   
3. When prompted, select the edition of Vista which you have purchased and continue with setup.
   
   
4. Once setup has been completed and you have been brought to the desktop for the first time, run the install program from within Windows Vista. This time, type in your product key when prompted.
   
   
5. When asked whether to perform an Upgrade or Custom (advanced) install, choose Custom (advanced) to perform a clean install of Vista. Yes, this means that you will have to install Vista for a second time.
   
   
6. Once setup has completed for the second time, you should be able to activate Windows Vista normally. You can also delete the Windows.old directory which contains information from the first Vista install.

Wow, nice guide

One question though...

So say your HD is totally blank, you deleted all the partitions...

Vista will install under the trial version without any prior OS?

... and after that you insert the CD again at boot, and reinstall, only this time by using the key, right?

Thanks

If you have the retail full version, or an OEM version, you can install Vista on an empty drive with no problems. This work-around is only for upgrade versions. When using an upgrade version of Vista, it first checks to ensure you're eligible for an upgrade by checking the system for an activated version of WindowsXP or Windows 2000. If no earlier version is found, it won't install -- unless you use the steps in this guide.

This could also be used, and abused by people to install the upgrade version on systems where it's not eligible. So, I don't know how long Microsoft will leave this hole open. However, we've presented it here because there are legitimate reasons for needing to perform a clean installation using an upgrade version.

Ah, ok, thanks I have the express upgrade coming in the mail because of the laptop, and I don't know if I should just wipe it or what. Nice guide though, thanks for sharing

This is also referring to the installment of Vista when you get a new computer as well?

This looks very familiar to the info I was warned about and now it is pinned here well isn't that strange Thanks I thought MS didn't go for this kind of install I guess things change.