I am downloading Windows 8 RTM using Microsoft's secure downloader provided by my school's DreamSpark account. The OS I'm currently on is Windows 8 preview. Once the download reaches 100%, it restarts to 0%. I open the download path folder, and find the en_windows_8_x64_dvd_915440.sdc file and the en_windows_8_x64_dvd_915440.scd.log file.
The log file contains only one line : "Unpacking File: C:\Users\en_windows_8_x64_dvd_915440.sdc" I was unable to unpack the file using 3rd party software, and there seems to be no official software made for unpacking this type of file.
What can I do to avoid downloading the OS illegally, even though I have my own product key?