How do I do a clean installation with the Windows Vista Upgrade media?
Regardless what many may think, Vistas install process is actually a clean installation whether you choose to upgrade or not, which only retains your applications and settings, no residue from the prior installed operating system is carried over during the upgrade. You might encounter issues with application and device driver compatibility, but would be just the same if you did a regular clean install and tried to install those applications and devices on Vista.