Yeah, I don't think the laptop is drawing a whole lot of power. even if the battery is completely dead, it will just be drawing about as much power as it needs. A lot of people using off-the-grid electricity favor laptops, both because they can charge when electricity is plentiful (daytime for solar) and use that energy when needed, and also because they tend to use a lot less power then most desktops.
But it's good to think about these things. A lot of our equipment/appliances draws power constantly, even when turned off, just to keep it in a ready-on state, or something similar. One of the things those Kill-A-Watt meters are good for, so that you can see how much energy your TV/dvd/stereo is using when it's supposedly turned off for the night. Some people will plug these things into a power strip, and just turn off the power strip when they don't plan on using things plugged into it for a while.
Good luck with it, hopefully the energy consumption concern is genuine, and not just a scapegoat.