The new Rev B 1.8ghz/128ssd MacBook Air is speedy and for some a suitable desktop replacement. One noticeable difference between the two is for example when typing in Google Doc's or posting on a forum with the MB Air there's a real lag from when you type a word and when it appears on the screen. With the MacBook Pro ('09, 2.6ghz, 320hd, 5400rpm) when I type the letters appear instantly... What causes this lag? Processor speed? Ram? I'm curious. I was getting used to the MBA working like this with the lag and never noticed it until I can see now with MacBook Pro there's just no lag at all?