[charlieluce]

I GM Pathfinder on a 4 year old Acer laptop with a 1.5GH Core i3 and originally 4GB of RAM (I upgraded to 8 eventually but it didn't make a lot of difference) and built-in Intel graphics. During games I've got Hero Lab, MapTool, a PDF reader, a browser, and various notes open at once and it works fine; my biggest complaint is that the low-end 1366x768 screen is not a lot of real estate, but it's adequate.

So you don't need a lot of laptop power to GM, though I'd probably skip the Atom-based machines and others with 32 or 64 GB of main storage.