I'd personally take a notebook, or an ultrabook, although most have low-wattage CPUs. Why a notebook? Better screen resolution, capable of doing more, netbooks are getting outdated and not worth the money, lower end notebooks cost around the same as a netbook, but can game casually, watch videos, etc.
Ultrabooks can have the screen size of a notebook, but are lighter and slimmer. Unfortunately, they are usually expensive. If you really want a netbook, you should definitely go with the AMD fusion ones, as they outperform the Atoms in terms of light gaming, etc.