Hello I have a doubt. In my PC I have installed Windows 7 Professional RTM 7600, Bios Slic 2.1 (Original untouched) Activated via Cert Installation and OEM SLP Professinal KEY with CMD. I just want to know if i can upgrade to Windows 7 Ultimate RTM 7600 (Original DVD with $OEM$ Folder and everything). Don't want to make a clean install, too much programs and docs to backup. "I have the original Windows 7 Ultimate DVD untouched too" Can use any of them? well if is possible to upgrade. little help here. Thanks PS: I think its possible but need to install OEM Cert and key again. But I'm Not sure..