Original post : Installing Windows Vista.
If you do not have a product key for Windows Vista, you can continue through setup to install a 30-day key-less version of Windows Vista by simply pressing "Next", and when prompted for a product key, press "No". Select the edition of Windows Vista you wish to install and check "I have selected the version of Windows Vista I have purchased".
You can provide a product key to the Windows operating system within 30 days of installation. This method is highly recommended for those of you planning on evaluating Windows Vista in a pre-production environment where you would not want to use an activation.
IMPORTANT: Formatting will erase the data contained within the selected partition. Please make absolutely sure that you have selected the correct partition before formatting.
The first time that you log into a new user account on Windows, the operating system needs to configure your user profile, create your user directories, and create your user accounts registry file. Subsequent log in attempts will be much faster.