Im getting ready to sell my iMac today and am using the money i get to buy a used macbook air. Money is an issue so a new one is out of the question. I have been shopping around and ive looked on mactracker but what are the real world differences between the 2011 and 2012 airs? i wont be doing much on it...mainly music and web browsing and photos...will i really notice any difference in either?