Windows 7

So, people are talking about Windows 7 all over the place now. It seems that some are saying that's it's the most stable beta Microsoft has ever released. While reading and viewing the pics on some of the sites, it would seem to me that Microsoft wouldn't build a whole new OS just yet. Wouldn't it make sense if they decided to release this as a service pack? It doesn't seem like there are enough changes in Windows 7 to justify a whole new version of Windows, like 98 or ME or 2000 to XP, or 3.1 to 95. I would have hoped that they learned their lesson from ME.
If Windows 7 was actually a Service Pack to Vista, everyone who already has Vista wouldn't be so upset that they invested in an OS that would otherwise already be retired. Wouldn't this make more sense, and fall more into Microsoft's campaign of disguising Vista as something else, and then getting people to like it [read Mojave Experiment]?
Just a thought. If they release Windows 7 as a service pack for Vista, then it would make everyone so much more happy about Vista, especially with the good reviews it's getting, plus some of the added features. This would also get more people on the Vista bandwagon (the positive bandwagon).
I'm looking forward to a more thorough examine of Windows 7 to see if it's really just Vista under the hood.