I am in the process of answering that. To start, I had installed this RC version of Windows 7 to a clean hard drive so there was no previous O/S installed, which means it has been running on a 'free' operating system. Also note it was the 64bit version of RC and the version being installed is Windows 7 Home Premium 64 bit.
I initially inserted the Windows 7 Home Premium DVD with windows running and attempted the install. It recognized the version and told me I could not perform the update.
I then restarted the computer, booting to the new Windows 7 Home Premium 64 bit DVD and started the 'install now'. Setup is starting, I accept the license agreement and at the Upgrade or Custom prompt I will first try the upgrade. This fails with the "compatibilty report" stating "The computer started using the Windows Installation disc. Remove the installation disc and restart your computer so that Windows starts normally. Then, insert the installation disc and restart the upgrade. (Do not select "Custom (advanced) to perform an upgrade." Custom (advanced)" installs a new copy of Windows and deletes your programs and settings.). I click Close.
Again, I click INSTALL NOW and accept the license agreement. (NOT doing what they suggested as I knew that would get me in a loop since I had already tried the upgrade option from windows already running).
This time I choose 'custom (advanced)' (even though this is exactly what I was told not to do)
Now I am greeted with the 'Where do you want to install Windows?" prompt with a list of all my hard drives, which I will choose the "c" drive where windows already exists and sure enough I am prompted with "The partition you selected might contain files from a previous Windows installation. If it does, these files and folders will be moved to a folder named Windows.old. You will be able to access the information in Windows.old, but you will not be able to use your previous version of Windows.
I click "OK" (since I know this is going to basically reinstall windows as a clean install and will save me a little time in transferring my data (documents, etc) since I do have everything backed up, if by no other means, Carbonite (the computers most important product beside the computer itself!)
At this point I have ruled out that you can not get away without at the very minimum, a 'soft install' of the O/S.
My next mission will be to attempt to change the product key from another computer running the same o/s (windows 7 rc build 7100 64bit) and it doesn't recognize the new key (could this be because it isn't ultimate or does it recognize the installed o/s is actually beta?) .. regardless, this method failed as I do not currently have an ultimate edition to try this out on.
Back to the computer that is getting Windows 7 Home Premium installed.. the first restart has happened after the windows files had been extracted.
Windows setup is starting services... and from there it installs normally. After the install I can simply move the old account files to the new account, but since this is basically considered a clean install, you will have to reinstall all your other programs, although the data from them can be found in the oldwindows folder as mentioned in the setup. I typically delete this once I have moved my data across.
