Both the i5 and i7 have integrated memory controllers, either 3MB or 4MB of Level 3 cache and "turbo boost," which means the chips can max out at clock speeds higher than the baseline numbers advertised. And they offer , which means the operating system "thinks" it can access four cores instead of two -- it's just that two of the cores are virtual. Having more cores, whether physical or virtual, means software and operating systems can process commands faster because the work is being done in parallel, not sequentially.

When it comes to turbo boost, the concept is pretty simple. In this 15-in. model, the processor starts out at 2.4 GHz and stays there unless taxed. If you get into some heavy data-crunching, both cores can throttle up to 2.8 GHz. Or if the software you're using is running on one core instead of two, that lone core can throttle up to 2.93 GHz.

It's like having a turbocharger on your car. If you're cruising along at 65 miles an hour and stomp on the gas, you'll feel an extra spurt of acceleration as the turbocharger kicks in. When you let off the gas, the turbocharger cuts out and you're back to basic cylinders.

Essentially, the system is squeezing out as much processing power as possible from the Core chips when that power is needed most -- under heavy load -- and then backing off the juice when it's not. The result is an elegant combination of power and thriftiness.