The 2 gigs is almost certainly your problem. Most photo software certainly CNX2 and Photoshop are memory hogs. 4 gigs would be a minimum, 8 gigs passable*, 16 gigs very nice. By the time you subtract out your system software and anything else running, you are probably only allowing CNX2 a bit over 1 gig.
*I run 8 gigs on my office iMac and home MacBook Pro and am very happy.
Jon Kandel A New York City Nikonian and Team Member Please visit my website and critique the images!