In case you haven’t been paying attention, there’s been a noticeable shift in the way Microsoft has been promoting its Surface line of tablets — instead of pitting it against the iPhone like it’s traditionally done, it’s started pitting it against the MacBook Air. This may seem a bit puzzling since Apple sells more iPads every year than it does MacBook Airs but it actually makes all the sense in the world, as an excellent analysis by ZDNet’s Ed Bott makes clear. While Apple doesn’t sell very many MacBooks per year when compared to Windows PCs, the ones it does sell are hugely profitable for the company. MacBook Airs and MacBook Pros are pricey items but Apple fans have shown