Hello all! I have noticed that Windows 7 has different ISO files, and I noticed that current official installation has the following details: File name: en_windows_7_ultimate_x86_dvd_x15-65921.iso SHA1: 5395DC4B38F7BDB1E005FF414DEEDFDB16DBF610 I saw that people say that the following ISO is also official: File name: 7600.16385.090713-1255_x86fre_client_en-us_OEM_Ultimate-GRMCULFREO_EN_DVD.iso SHA1: 9018d76cd7eb1098257f8474d9d7d40af948e143 My question: what is the difference between these two files? What is the exact difference? And are both official? Thanks for help.