anything but dell. My office purchased some 8-10 dell laptops at various times, over the last couple of years. Every single one of them, the battery has died within 1.5 years. I also know 2-3 others outside of office who have bought dell laptops who have sufferred the same fate. One or two incidents I would have said it's bad luck and all that, but this problem appears to be endemic.
I think this is common amongst my friend's as well. It has failed after an year and before 1.5 years. However my Dell laptop has been going strong for 3 years and still get about 1.5 - 2 hours of battery life. It's my download rig as well. I regularly disconnect the battery from the mains power to allow it discharge and recharge, this way the battery would be fresh and run long.