I need some shopping advice please. My laptop battery is on the way out - manages about 20mins from full charge. However Dell want me to pay nearly £150 for a new one. I promptly googled instead, but am so confused! Please can someone explain what would be the best voltage and capacity? Is a 4 cell sufficient or would a 9 cell be better? If I get a different one to the one currently in the laptop (cell/capacity-wise) will it fit? Are they all the same size? Help please! I am so much more used to double As!