There's an app called 'pig' that was written by a forum member that takes up 1 gb of ram at a time (you may have to search for it or send me an email). If you run 7 instances with 8 gb installed and your computer doesn't stall out, you're accessing all 8 gb without a problem. My 2.4 gHz MBP (non unibody) can only access 6 gb and after 4 gb (i.e., 4 instances of pig running) it brings it to its knees.