Hello,
Im a PC user since more than 10 years and purchased a Macbook Air 13" in early 2012 which I used for 3 months and then upgraded to a Macbook Pro 15" retina since the last 5 months. Both device are above average performer in their categories and both of them was more than enjoyable for me.
If you plan to use for more than 3 years, don't really focus on ultra portable and don't mind refurbished (As I did for my Macbook Pro Retina), I would invest a bit more to get the Macbook Pro Retina 15" 2012 mode available here:
http://store.apple.com/us/product/FC975LL/A/refurbished-macbook-pro-23ghz-quad-c ore-intel-i7-with-retina-display
Macbook Air is a really good laptop (More focues on mobility) but the retina display of the macbook pro line simply blow the competition. Put them together as I did and you brain simply go toward the retina display of the macbook pro. For the price difference between a Macbook retina 13" and 15" and the amount of time you plan to use it, I would strongely suggest to get the bigger one. You will enjoy a 128 to 256Gig SSD upgrade, bigger screen, real quad core i7 processor and dedicated graphic card to push all of thoses pixels and games.
The 300-400$ difference at purchase time is a bit rough if you are on a budget but you will regret the expense in a couple of months.
Feel free to ask any question.
Thanks
