I have narrowed my purchase options to two iMacs; the 24" or the 21.5" iMac, the loaded versions (both having the 3.06ghz and 1tb). My use will consist mainly of writing a dissertation and watching movies for entertainment. Other uses will be storing and manipulating photos and maybe video/movie editing in the future. Which computer, i.e. display/screen choice would you go with, and why? Thank you for your thoughts.