I am aware that the same CD is used for all versions.. now the question say I have w7 home premium pre-installed (oem) that came with a machine (it has a valid slic in bios), to upgrade to say ultimate do I have to go through another install (or upgarde?? with dvd ithout ei.cfg) ) or are all the files installed but just needs an ultimate key (oem) installed ..
You can do a Windows Anytime Upgrade from Home Premium - all you need is the Ultimate key - conveniently listed on this site. It will do an inplace upgrade to Ultimate without a re-install.