Yes, the beta keys are only for Ultimate, like a previous poster said: go into the iso and delete ei.cfg to do this, extract the ISO to your hard drive then open the folder where you extracted it to and go to the "sources" folder and find and delete the ei.cfg file. Now open setup.exe (back in the main extraction folder), you can now install whatever version of Windows 7 you want (in this case, it's Ultimate)
Cheers,