For those interested :
Rest here :http://www.theinquirer.net/default.aspx?article=35876
WAS able to update from RC2 to Vista RTM from Vista itself. I tried it for fun and I was surprised that it actually works. It takes more than an hour to finish up but it does the job in the end.
Just for a comparison it takes about twenty-five minutes to install a clean version of Vista RTM on a machine.
It was funny to update the operating system and to be able to use the abilities of Aero glass and flip the Windows all the time. This doesnâ€™t speed up the installation process but it certainly makes it more fun