This thread prompted me to weigh mine as well as the tiny power adapter for my 13.3" Carbon Fiber VAIO X.
The results were interesting. I got 6.7 for the Mac adapter & just 4.2 for the VAIO. When checking the combined weight of each laptop & it's power supply the Sony was lighter by 7/8 lbs.
Both these are very nice machines. If I was limited to just one, it would be the Mac without a second thought. I like the style and fact that Apple's always been my favorite.