you need to also consider that PC's are generic.
Apple can tout the 'it just works' mantra because as we all know, Apple are hardware manufacturers first and foremost.
The benefit of this is that Apple can dictate design and technology and then code to suit as we've seen from all its offerings over time. Because it can dictate the system architecture and then tailor the OS around it, it has the luxury of design freedom which other manufacturers don't have.
Ultimately whatever windows box you choose, they are all somewhat generic as a platform, the chipsets being an across the board configuration hence the boards having the same number of slots, ports et al, irrespective of manufacturer.
Windows has to work in all of these circumstances, so in truth, windows 'just works' because it has to install on possibly a thousand different machines all with different junk in the cases, even though the chipsets work on a common framework.
Apple doesn't have to do this, nor does it have to play device mfr catchup as it does both.
Imagine you are the designer, instead of being shown a motherboard and told - wrap it around this, you design the aesthetic and tell the engineers - how can we design to fit into this...
that is a powerful and privileged position to be in. Take the Air, perfect example.
The style was designed, and the motherboard was conceived from the ground up to fit into it - 'lets just break the ssd apart and lay all the chips side by side'. genius.
That's apple's powerful advantage. for another to do the same they have to re-invent an entire chipset potentially. Yet this is why Macs just work, because the OS is designed to take advantage of the hardware, which is designed and engineered to take advantage of the style.
Although I don't advocate it, if you ever tried to get OS X to run on pc hardware then you'll understand perfectly what i'm talking about. Intel chips or not, OS X doesn't run on generic hardware without a lot of dicking around.
But in truth it's never needed to.
That's why there are no real competitors to go head to head with apple - yet.
Apple's true strength is innovation, an eye for design- having learnt the hard way. I remember the days of the Performa range. When iMac came out it changed everything.
But what keeps Apple at the forefront? - easy. Apple don't play the numbers game. Lets face it, most new smart phones rip iphone apart, however Apple shine at taking something that is technically complicated and making it very easy to use and work with, And that is Apple's greatest strength, from iLife to Disk Utility to iOS, the user experience is simplicity itself, it doesn't intimidate, it doesn't make people nervous. It draws you in with beautiful interfaces and nice product design, and you feel at ease working with it. That's what makes mac users productive.
On windows, I'm always fidgeting with settings and dicking around because in truth I never really feel comfortable using it. with my Mac I just concentrate on what I need to do, and enjoy the fluidity of it all.
I just work!