"If Vista is run in full Aero mode, with none of the Vista-provided power management settings turned on, it is likely to demand more power, and have an impact on battery life," said Dell spokesman Ira Williams, in an e-mail interview. "That said, if you run Vista in battery-optimized mode (using a non-3D interface), we would not expect the battery life to be significantly different from XP in that scenario."
Techreport did a fairly thorough examination of the impact that Vista's interface has on battery life. While a drain of 20 minutes would have been shocking, the actual results were even moreso. As it turns out, they found almost no difference. Not only was system battery life not impacted, but power consumption changes were quite short:
In all, none of our configurations consumed more than an additional watt moving from Vista's Classic to Aero interface. Power consumption did spike by between 10 and 15W when using Aero's 3D window switching feature, though. This spike didn't last for much more than a second, so it's unlikely to have a significant impact on overall system power consumption or noise levels. In fact, none of the cards we tested with variable-speed cooling fans even ramped up their fan speeds during our Aero testing.
All in all, the concern about Vista's interface being an energy hog seem to be mostly unfounded. While there is a root of truth behind them, in that a system consuming more resources obviously needs more power, modern hardware seems to be impacted to a minimal degree by it.