Hey dudes. I have a laptop with Vista Home Premium, which came with the "free" Windows 7 upgrade. However, the upgrade package doesn't ship until late november... If I wanted to install Windows 7 now, and then just update it with the legit key once the upgrade finally shipped, without having to reformat and reinstall, how would I go about to do that? Which version would I need to install (Retail, OEM)? Thanks!