I'm not sure why I'm getting into this discussion - other than maybe boredom - but the one thing to remember when having any of these "my laptop/pc is better than your laptop/pc" discussions is that the Apple offering comes with OSX and any other does not.
So the discussion becomes moot if you really want OSX. In the case of the MacBook Air, I and most others on these forums want OSX. (hence the name MACrumors.com)
Don't get me wrong, I do not think badly of Windows7 (except were WiFi is concerned but that's a whole other discussion/rant) and in fact, my desktop PC is a full-on, bad-ass, Windows7 running, over-clocked, gaming PC. Also, I am a computer consultant and spend a lot of time installing, networking and troubleshooting Windows PC's and servers. Overall, Windows is okay.
But again, on this site, it's OSX that people usually want. Yes your new Sony VAIO Z is a sweet little laptop that certainly out-specs any current MacBook Air. Maybe Apple will address this on Wednesday (we can only hope!) and maybe they wont. Historically, Apple hasn't always seemed to care about being the performance leader when it comes to their laptops. They do, however, build pretty solid, well engineered products, with a style that screams "I'm a Mac!" And, most importantly, they run OSX.
For me, that is the most important thing. I want my super-thin, light laptop to run OSX. The software I choose to run on it is either only available for OSX or I think it runs better on OSX (an example would be the Remote Desktop Client for OSX - it's so much better and more stable than the one that comes with Windows.
I realize that I may be spending more money than an equivalently spec'd Windows laptop, (the so-called Apple Tax) but I love my Air and its thin, aluminum construction and... it runs OSX.
So after all of that, I hope your new Sony Z brings you all kinds of happiness just like I hope whatever gets released on Wednesday by Apple brings me all kinds of happiness! Maybe it will even be Magical Happiness!
Later all...