I recently did power consumption test for my Acer 1810T, which I bought a year ago.
OS desktop is Windows 7 Home + Aero enabled.
I used Kill-A-Watt power meter.

The Numbers

Off and charging: 21W
Idle at desktop + charging: 29W
Idle at desktop: 10-11W
Half load (one core): 16W
Full load: 22-23W