I just picked up a refurbished MBA Rev. A and love it. With the exception of slight warp in the case (the left foot just ever-so-slightly sits above my desk) which I'm told can be fixed with light pressure, it is perfect. Apple has agreed to either refund my purchase or send a replacement so I'm probably going to swap it out.
Anyway, I'm coming for a history of Dells, usually those big XPS units or packed Inspirons, and I can't get over how different the experience is on a Mac.
A big part of that is the hardware. The keyboard is stunningly good and the display is amazing. I own a Pioneer Kuro plasma and the MBA screen always reminds me of it. Dark, inky blacks. Processor-wise, I can tell that I don't have the performance I used to but I don't really care.
Earlier today, i was sitting around writing an assignment in Pages and had it set to full-page view. Just a white sheet on a completely black background and it looked amazing (given the screen's high contrast). No taskbar, no pop-ups, nothing. Just a plain white sheet.
Something about the ease and simplicity of the Mac software makes me feel more productive. Maybe I'm not...but it's a lot more fun.