Microsoft has released instructions for users planning to upgrade to Windows Vista.The upgrade options are dependent on the version of Windows that you are currently running. The table below outlines the upgrade options mapped to the different Windows Vista editions
The two upgrade options available are described below:
You can upgrade in-place, which means you can install Windows Vista and retain your applications, files, and settings as they were in your previous edition of Windows.
Upgrading to Windows Vista with a clean install means that you should back up your files and settings, and then install Windows Vista. After the installation is complete, you’ll need to reinstall all of your applications and load your backed up files onto your PC.