I wouldn't recommend downloading potentially illegal disk images from the internet, you do not know if they are genuine or have viruses.
Are you 100% sure this works? I remember trying to use my OEM Win 7 CD and type in the Win 7 product key on my brother's Alienware m11x laptop and it didnt work. I had to use the Alien Respawn and get bloatware like MacAfee Antivirus. Yes, product key for laptop and my OEM DVD are both Home Premium 64 bits.
Yes, you can use a regular Windows 7 retail DVD and a genuine Windows 7 OEM product key to perform a "clean install"> However, when it comes time to perform product activation, you'll need to use the "activate by phone" method.
A Windows 7 installation DVD incorporates both retail and OEM license agreements. If you use a genuine Windows 7 OEM product key, it will unlock the OEM license agreement. If you use a genuine retail Windows 7 product key, it will unlock the retail license agreement.
That's a lot different from Windows XP. With XP you had to know if your key was for XP-Home-original-without-a-service-pack, XP Home SP1, or XP Home SP2 (never ran into a key from SP3). So when trying to re-install Windows XP for a friend or relative who's HDD failed, sometimes I had to install Windows XP three times before I found the version that would take the key from the sticker on the side of their computer. What a pain, that XP keys were "keyed" to the exact service pack version of XP.