I've just been having a play with the Beta myself, I honestly can't say it's much quicker, took as long to install - I think, I didn't time it. I really, really, really do not like the start bar, it looks crap compared to Vista's. It feels marginally quicker under VirtualBox but with no support for the drivers, plus being a time-bombed (I believe) beta it's not really worth investing my time and energy playing with it too much. Not overly impressed and I've just deleted it now rather than later.
After playing with Windows 2008 too, I've come to the conclusion that it's better just to stick with Vista, even though the virtual disk is eating 14GB of my Mac's hard disk to run just 3 apps I use. Terrible waste of space really. XP would be the more efficient choice.
I think Microsoft have just got it wrong with Windows, a lot of space is used for a bloated, slow, feature-less, application-less environment out of the box, critically dependent on heterogeneous 3rd party apps to get any level of usability which paradoxically increases the risk of system non-usability. Essentially a bloated application launcher compared to OS X, workflow is neither graceful or efficient. I see no innovation here just poor imitation and a perennial striving for what they so obviously cannot achieve. People have not responded to Vista, so what's the solution? More of the same. People didn't like all this 'Basic', 'Home Premium', 'Business' and 'Ultimate' nonsense, so again the solution is yet more of the same.
In short, I've always said 'DONT GET A PIG TO DO THE JOB OF A LEOPARD'*
(modify: Panther, Tiger, Snow Leopard etc as appropriate)
How does Windows 7 compare to OS X? Really? It compares just like every other prior version of Windows, and I'll predict any to come - poorly, because Microsoft just lack a certain something that Apple just GETS intuitively. Microsoft for all of their money cannot buy it, they can't acquire it or develop it over time, it was there from the very beginning. It's why Apple are still here all these years on and Microsoft are STILL trying to be like them and STILL missing the mark every single time.