I'm about to purchase my first mac, and im still debating between the 15-inch: 2.4GHz and 15-inch: 2.53GHz models. I'm not exactly sure on how to justify the 2499 model. What is L2 cache and how does having twice the amount of it make a difference on the system ? Is there a big difference between the 2.4 and 2.53 dual cores ? "NVIDIA GeForce 9600M GT graphics processor; and NVIDIA GeForce 9400M graphics processor with 256MB of DDR3 SDRAM shared with main memory" - Does this mean that is comes with two video cards ?