I now swear by monitor hoods. Like night and day!
Just to add to Snoogly and David's comments, when I've seen sports photographers editing the work during the day at outside events, they always have hoods around their laptop screens.
One further question Termite:
Unless this is just for occasional edits or use on the move, is there any reason you won't use an external monitor?
I've seen so many people develop neck, wrist and posture problems by trying to use a laptop in a desktop environment. Of course, if you're going to be doing this whilst working away from home, in cafes or hotels, I can understand though.