Essentially, if you go with the $599 one, you may have issues doing video editing, rendering, etc which you will have if you edit video from your go pro.
More ram will "help" but I'll give you an idea what things look like in the video world.
Right now, I am exporting a video I made for my youtube channel. Nothing really crazy, just compression and formatting. I am running a Mac Pro with 8 processors, 16GB of ram and 3.4 TB of hard drive space. As the project is being rendered... I have 10.14GB of ram that is not in use and I am running at 75% processor load.
So in reality, the slower processor with more ram might handle some things, if not all, the quad core i7 will handle more, faster. Add more ram and things get snappier.
Also, my mac pro is the highest rated pro of the year it was made (2008) and it can still run the latest OS, accept all upgrades I can throw at it, and runs like the day it was new.
I understand you are not well versed in computer tech, but think of it this way...
A little more invested in parts you cannot change (processor) while upgrading what you can later (ram/Hard drive) would be more beneficial in the long run. If you just want to try a mac out, with minimal investment the $599 will do everything you need. If you think you might upgrade to something like an iMac in a year if you like it, get the $599 one. If you are set on not buying another for 3 to 5 years, spend a little more and get the i7 and upgrade it further to the highest spec i7.
Last edited by kaput; 12-27-2012 at 10:34 PM.