One of the most frequently asked questions for the "upgraders":
You have met the requirement by having the OS needed for an upgrade.
http://www.microsoft.com/windows/products/windowsvista/buyorupgrade/upgradepaths.mspx
(For instance XP Pro to Vista Home Premium)
A 'clean-install' is required by your upgrade path and MS failed to provide
a method of doing this required 'clean install' with their upgrade disk.
So, MS answers with a set of instructions:
http://support.microsoft.com/kb/918884/en-us
But if the path you desire for upgrade is not available, the Upgrade button
is disabled. and you must select Custom Install. Unfortunately, this will
not work with Clean Install Method 1 or Method 2 unless you fail to insert
the Product Key on the first installation. (Which they conveniently forgot
to
tell you because it allows even those without a valid OS for upgrading to
perform this install at a substantial price reduction.)
I'm not promoting cheating MS out of their money for a Full Installation
disk
(Product Key,) but if you meet the requirements for an upgrade, then you
should be able to upgrade with the disc they provide.
In a nutshell:
This method erases ALL data from the selected drive!
Boot from the DVD and select Custom Install.
Format the drive and install Vista (version you bought) without entering
your Product Key.
When it is all done, while running Vista from the Hard Drive, open the
DVD and install again, this time selecting Upgrade. (Total time: about 1.5
hours on my machine.)
Don't bother installing software/updates until you complete both installs.
Are there any drawbacks other than having to install twice? No.
It's the same full installation.
The same issue occurs with the Anytime Upgrade. You are provided a
downloaded "License" and not a Product Key. If you should ever need
to re-install, you will find yourself going through the installation at
least
twice to get to get to the final upgrade you bought.
Instead, use a third party program to determine your Product Key, or open
the license with Notepad and extract your Product Key so you only have
to install once next time.
