windows 7 upgrade from vista

Hello, all

I have another computer(a desktop) which came with Vista, for which I will be purchasing the win 7 Home Premium (upgrade version) in order to upgrade from Vista to Win 7 HP 32 bit. According to the instructions on the MS website for installing the upgrade version, everything should go smoothly, and be able to retain all programs, settings etc. and not lose anything in the process. I have checked compatibility with my existing hardware and programs, and everything I currently have is good to go. Also, more than sufficient RAM and HD space for the installation.

1. Is MS's claim about not losing anything correct, or have you had reports of anything in particular of something being compromised in the process, even though the installation went smoothly?
2. In the event something glitches and I have to call the Activation Center, can the installation still be completed with everything retained, or will it be the same as a manual install where everything is wiped, and I have to start over?

Thanks for any help!