I would also love to know whether original or new MBA and if new, is it SSD. I think the real reason I use my MBA all of the time is because it's a new model with SSD. I am so impressed that with a much slower CPU, it's so much faster with the SSD. When I had the original MBA, it was my third option that I would use only for email and writing.
I have a unibody MB that never gets used. I bought a 2.33 GHz MBP w/256 graphics as my Windows machine and as my kids gaming & video machine. I have to use Windows one day per month for a client app. Other than that, I use my MBA ALL of the time. I am simply amazed at the power to be a desktop when plugged into my ACD, and the extreme portability when I take away from my desk.