I've got a 2GHz CD macbook and I upgraded the hdd to a 7200 160Gb hdd a few months ago. The battery life was pretty good, nothing that stood out as out of the ordinary, but lately it's been absolute crap. I keep the wifi on all the time (nothing unusual, i've always done that) but from a fully charged state, my battery life is zilch. The other day I had it fully charged overnight and in the morning I synced my ipod and closed the lid and went to work. (power still on, but I guess you'd call it "hibernate mode"??) and by the time I get off work, it was completely dead. So that led me to believe something was definitely wrong. I have a widget that gives me the cycles and battery health and it's at 100% still, so I dunno what it could be. Has anyone heard of a batter that can send a signal that it's still 100% but really not be? This was a replacement battery from apple when they had battery health issues and its never dipped from a 100% health.