"he used Windows XP 100% of the time; that battery died about 6 months ago, suddenly just stop accepting charge and you could only work with that computer retiring the battery before plug it in.
My conclusion? Windows kill batteries"
i remember a identical story with a hp laptop here on this forum but using pclinux so pclinux kills batteries too
in a manual i found that it was recommended to remove the battery if you work all the time connected to the wall
on another manual i found that it was recommended to keep the battery in place because charger and internal system stops charging battery when it reaches 100% so all is ok
on another one i found that you can remove the battery with the laptop turned on, and on another one you do that and the laptop will explode, i tried to make it explode and failed miserably
the battery on my netbook seems to have lost charge on this 11 months i had it, supposedly it has lost 10% of the original capacity, this is reported by linux and windows xp(hwinfo free tool can give you this information)
i sometimes leave the laptop connected all the day and sometimes disconnect it when it is completely charged and let it discharge but rarely i leave it drain completely, reach charge under 4%, only a couple times i left it go to 0%
the logic says that if you are not using something, just remove it/unplug it