Windows 7 was established early, even in 2007 as the successor of Vista and the next iteration of Windows. In early 2007, following the consumer launch of Vista, Microsoft wasn't talking Windows 7 much.
Things of course evolved a tad throughout the past year. There was talk of a 2010 launch, and even MinWin, the kernel of Windows 7 was demoed, with the leaked video of Eric Traut, Microsoft Distinguished Engineer, becoming the first official confirmation of the work being done on the next version of the Windows client. In January 2008, Microsoft managed to let the Windows 7 genie out of the bottle, by shipping an early testing milestone to key partners.
Details about the operating system began pouring in, accompanied by screenshots and even videos. One of the arguments being used against the validity of Windows 7's proof of life (1, 2) was its similitude to Windows Vista. Windows 7 Ultimate Edition Build 6.1 (Build 6519.1.x86fre.winmain.071220-1525) is indeed still Vista for the largest part. The evolution from Vista was implemented almost exclusively under the hood, and in this context, the graphical user interface, Windows Aero, will be among the last details about Windows 7 to be altered.
But there is also another reason for the close resemblance of Vista and Windows 7 M1, revealed TGDaily. And is related to the fact that Windows 7 M1 is not a standalone product. It has to be installed on top of Windows Vista. Not only does it need Vista as a foundation, but actually it only deploys on top of Windows Vista SP1. The same Microsoft key partners that got a sneak peek at Windows 7 M1 also received the gold bits for Vista SP1 ahead of everybody else.
Windows 7 M1 comes as a ISO DVD image weighing in at 2.7 GB, and is designed to be tailored on the Vista copy it installs on. This is why the Windows 7 M1 appears to feature the Ultimate edition. This is in fact a reminiscence of Vista SP1, as is the kernel. At this point in time, it is clear that Microsoft has not implemented the MinWin kernel in Windows 7.
Microsoft, Windows 7, Windows Seven, WinMin, Win7, Windows Vista