If you have not seen it, go and checkout the OLPC project. Technologically it is superb: The screen is revolutionary, having two display modes (a 800x600 colour display mode and a 1200x900, 200DPI black and white mode that can be used in direct sunlight). The wireless networking can create a mesh to connect children and share any internet access between them all. All the software is Free (as in freedom). You can get hold of one now using give one get one.
I know this will not solve all of the worlds problems, people who have no food to eat or are in a war zone will not benefit from having a neat little laptop. OLPC is not simply a charity project, it is made to be useful to children and low cost (governments all over the world are signed up to buy them). Education can make a real difference to a society once the basic necessities are met.
I saw on the TED blog a talk by Andrew Mwenda on why aid is not the answer to problems in Africa, economic growth is. I agree, particularly after seeing the wonderful presentations by Hans Rosling (first , second) also at TED. Please do watch these as they are inspiring and really show the power of good data to shed light rather than heat on complex situations. Go play with the data yourself at gapminder.org .