I have a 4 year old Dell laptop that I bought new in the Summer of 2007 and then hardly ever used it for a number of reasons. I has always worked fine and still works fine. In total it less than a month's use on it. I usually use Linux on it but it also has a Windows partition that rarely gets used. I decided to get it out and update Windows. When I turn it on now I get a message on the screen in Windows that the battery can still be charged but is nearing its useful life and should be replaced soon. Is this message time triggered and related or does it really sense a worn down battery, maybe by the amount of current it draws to charge? I'm think it almost has to be it's age but would the system know if the battery was replaced? This was a top of the line model when I bought it. Much of the hardware was so new that it wasn't well supported by Linux in 2007. I had the choice of Windows XP and Windows Vista and thought since I'm not going use Windows much I'd like to see how Vista works. Well the few Windows programs that I was interested in using wouldn't work with Vista. I put the laptop away and continued to use my old computers until bout a year and half later when I bought a netbook. It has worked so well I never got the laptop out to use. This past Xmas I bought myself a new laptop. Not an expensive one but one I knew was well supported by Linux. It's as fast or faster than the high end model I bought in 2007. It feels flimsy but it works and it's fast! The 2007 laptop is now completely supported by Linux so it has no problems but I'm not sure how to take the battery message in Windows. The battery does fully charge.