I am looking for a macbook air mostly for general classroom use (web browsing, Word, e-mail) as well as some development work. Specifically I will be using both SAS (Statistics package) and Visual Studio 2010/2012 in Parallels. The 2011 version of the air is about $250-$300 cheaper than the 2012. The only difference that appears to impact my requirements is the 4gig maximum RAM vs 8 gigs. Is 4 something I can be reasonably happy with, or is 8 an absolute must? Thanks in advance for any advice.