I'd like to know whether Windows 7 Professional UPGRADE will allow a user to upgrade an existing system by installing clean on a fresh drive attached to a system with an upgrade-qualified previous OS such as Vista Ultimate Edition. For our environment, it's important to preserve the ability to revert to the previous system for a while until confidence in the released Win 7 product is established. So the preferred upgrade path would be, install clean and migrate user state.

redantison - The Windows 7 installer can't install Windows 7 on a bare drive using the product key supplied with the upgrade kit. Like the Vista installer, it has no means for validating a previous OS based on a supplied product key or CD. Instead, the Windows 7 installer must be run from a previously installed OS. It looks at the OS, validates it, flags the hard drive that it's eligible for an upgrade and then reboots. Whenyou then reboot from the DVD, it checks the state of the hard drive for that flag and then allows you to upgrade using the upgrade product key. Now, if you were setting up a dual boot option - that would be another story all together. You can install Win 7 on a 2nd hard drive or partition in the system. You would have to do a custom install and tell it to install the files onto the other drive. That is the offical position... However... Where there's a will, there's actually a way. Google is your friend. There IS a means to do it but it's not appropriate to discuss in these forums as it can be viewed as an invitation to violating your EULA.