The general consensus is that Vista substantially decreases battery life on notebooks. That is, with the new Aero Glass interface enabled.
From independent testing, some notebook users have concluded that Vista draws 20% more power with the Aero Glass interface disabled. With Aero Glass enabled, expect your notebook to run for much less than the quoted battery run-time. Four hours of battery life under XP just decreased to two and a half under Vista.
Isn’t mobility the whole purpose of a notebook? I mean there’s other purposes, but a vast majority of notebook users would agree that portability and mobility are the key reasons behind a notebook purchase. With Vista, I guess we can remove mobility from the notebook equation and hope there’s always a power outlet nearby. Or, we can keep running XP until drivers and hardware with better power management are developed.