The real important number is going to be you mA-h <-- amount of power / time
You also want quality cells, I know that my spare dell laptop that i let friends use has an awesome battery and it was made all the way back in 2006, its on the factory battery still! Its because it uses Panasonic cells. Quality cells can take the stress of constant charge and discharge.
this is what it looks like just in the off chance you have never seen inside one