I encountered this error last night but I can still use my Eee PC running Windows Vista. It lasted 2 hours 30 minutes after a full charge with no wifi, brightness at 1 bar and high performance power plan. Previously, without this error, no wifi, brightness at 1 bar and power saver power plan, it lasted 2 hours 15 minutes. This seems strange. Running Windows XP also lasts 2 hours 15 minutes. Since Windows Vista does not provide better power management, I suspect that the ACPI XP driver is not working properly so I remove the driver.
After removal, the system tray icon to change resolution to 800x600 is also removed. Also, Fn+F3 & Fn+F4 to adjust brightness will not show a visual indicator but it still works. Fn+F7 (mute), Fn+F8 (decrease) & Fn+F9 (increase) volume do not work but you can still adjust through the volume icon at the system tray.