I'm leaning towards picking up a Macbook Air, but cannot justify the additional cost for the SSD model. This is going to be a second computer for me, as I use my desktop primarily. The MBA would be used for web browsing and email when my son is sleeping in my room (where my desktop is). For such light use, is the 4200rpm really that big of a deal? Sure, it's slower than the SSD. But it is slow to the point where I am going to regret purchasing it? Anyone who has this model, I'd appreciate your thoughts.