This may have already been answered, but I can't find it though I searched. I have Windows 7 Home Premium retail installed and activated - I bought it. Now I'd like to upgrade to Ultimate on a Dell Inspiron 1720. I've patched the BIOS and got SLIC 2.1. I added the Dell certificate. Can I just change the product key to get Win 7 Ultimate? Or do I need to install Ultimate and enter the OEM key during installation? Thanks.