upgrade from vista home premium to vista ultimate

[GilbertsGrape]

I want to upgrade from vista home premium to vista ultimate. the home premium came pre installed on my dell. and my works provides it's employees free vista ultimate. when i put the install i do not get a upgred e option i only get te option for custom fresh install. i want to upgrede so i dont have to reinstall my aps and docs. how can i do this from the vista ultimate full install dvd?

[bbrian]

I haven't done this, but as I understand it you can upgrade without even running through an installation. If you go to system options and change the product key I believe Vista will turn on the additional features (and probably ask for the installation disk to copy additional files).

[GilbertsGrape]

now that would be just too cool i'll give it a try. have you read any where that it would work?