Not so mention that hackers cracked the key generating code for Windows 7. Same with MS office. They generate codes and try them until one works, and bingo you've got a legit code.
They've never cracked the key generating code for Windows 7. They just found ways to work around it.
In late 2001/early 2002 somebody figured out the algorithm to generated Volume License keys for Windows XP, and those don't need activation (so that companies with lots of computers don't have to activate 30,000 units). Starting With Windows XP Service Pack 2 Microsoft changed some things so that those generated Volume License keys wouldn't work any more. So you have to find a legit Volume License key somewhere (not all that hard to do).
Starting with Windows Vista, and continuing on to Windows 7, Microsoft changed things again. Microsoft changed the system for Volume License keys, making them not a viable option for pirates. Windows installed on OEM PCs was now using a system that referenced information in the computer's BIOS. Google "System Locked Pre-activation". So people just started flashing their BIOS with the necessary stuff. Windows thinks my homemade PC is a Dell.