How can I install Windows Vista without supplying the product key?
Yes, you can, sort of.
You can configure Windows Vista to install without having to manually enter the product key during the setup process. This is quite useful if you find yourself in need to perform an installation of the OS but without having the (legal) product key with you at that very moment. Unlike previous Windows versions where you had to have a CD Key handy during the installation of the OS, the Windows Vista setup process only makes it appear as if you have to enter a product key to install it.