Anytime you can add mAh to your laptop...do it...if the battery fits.
You may also want to be a little proactive in replacing the battery when the battery life starts dropping to about half of new battery running time. Even with the new materials in batteries, they still tend to wear out after a year or so, and when they wear out, they usually drop fast. The instructions say to use laptops exclusively on battery and plug in the charger when the batteries get low. But much of the time the battery gets low at inconvenient times..so I usually wind up using the a/c cord most of the time.
Just my $.02.
